CA1212772A - Aircraft flight data display system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

In order to provide timely aircraft performance data from an aircraft flight data recorder in a useful format, a flight data display system is provided: with a data storage unit; an interface circuit for reformatting flight data from the flight data recorder; a central processor for converting selected portions of the reformatted data into engineering units and storing the converted data into the storage unit; and a video display unit including a keyboard for selecting the desired portions of the reformatted flight data for display on the video display unit.

Description

AIRCRAFT FLIGHT DATA DISPLAY SYSTEM
BACKGROUND OF THE INVE~TION

The invention relates to the field of aircraft 1ight da~a display systems and in particular to flight data display systems that can visually display flight data directly from an aircraft flight data recorder.
Most of the commercial aircraft flying today are equipped with flight data recorders for recording var-ious aircraft flight parameters such as altitude,airspeed, heading and engine data. The primary purpose for recording aircraft flight data is to provide flight data for accident analysis but the flight data recorded on the aircraft has also proven useful to airline man-ag~ment for other purposes including aircraft mainte-nance and incident analysis such as a landing approach resulting in a hard landin~ or a go-around. With the advent of modern digital flisht data recorders that are capable of storing over a hundred different flight par~neters, the usefulness of the data to the airline operating and maintenance personnel has xpanded dramatically. The availabili~y of a large number of flight parameters has made possible significant improvements in the safety as well as economics of flight operations by permitting management to analyze actual flight data. However, in order to be useful, this data must be made available to management in a timely manner and in useful formats.

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A review of the prior art methods for producing aircraft flight data from a flight data rec~rder for analysis by airline personnel has revealed a number of significant disadvantages in these methods. Typically the data from the digital flight data recorder, which is stored in bit serial form, has to be converted into a format that can be used as input to a large mainframe computer system. After the data from the digital flight data recorder is reformatted, the mainframe computer system converts the data into the appropriate engineering units and this data is then printed out in tabular form or plotted for analysis. This process has several disadvantages one of which is a substantial delay in making the data available. For example refor-matting or transcribing the data typically takes sev-eral hours and further delays often occur because the transcription equipment is remote from the location of the large mainframe computer. Also it has been found that the use of the company base computer can lead to priority problems where the data conversion and tabu-lation processes quite often have to compete with other business functions of the machine resulting in further delays.
Along with the delays in making ~he data avail-able, a further disadvantage of the curren~ procedure results from the fact that large quantities of computer printout are produced requiring extensive engineering time to examine and analyze. Thus the processes historically used by airline management to obtaln flight data lacks the flexibility to present timely data in a form that would be most useful to operating and engineering personnel.

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S~MMARY VF THE INVENTION

It is the object of the invention to provide a system for displaying flight data from an aircraft - digital flight data recorder which includes: a data storage unit; an input unit for accepting flight data from a data storage uni~; a processor for converting selected portions of the reformatted flight data into engineerins units and storing the converted flight data in the storage unit; and a video display unit including a keyboard effective to cause the processor to select portions of the reformatted flight data for conversion into flight data engineering units and to display the converted fliyht dataO
It is an additional object of the invention to provide for the direct display of selected digital flight data from an aircraft flight data recorder with a system that includes: a data storage unit; an input unit; a processor for converting selected portions of the flight data into engineering units in response to a sync word in the data while flight data from the source of flight data is being stored in the data storage unit, and a display uni~ for displaying the dat~ converted into engineering units.
It is a further object of the invention to provide for the direct display of selected aircraft flight parameters from an aircraft digital flight data recorder with a display system that includes:
an interface circuit connected to the flight data record~r for converting serial flight data into flight data words; a data storage unit for temporarily storing the data words; and a data processor for causin~ the interface circuit to input serial flight data from the flight data recorder and to convert the serial data into a word format, storing the flight data words in a first predetermined location in the 7~7~, data storage unit, converting said flight data words into scaled flight data, and s1oring the scaled flight data in a second predetermined loca~ion in the data storage unit; the system also includes a S display unit responsive to the processor for visually displaying the scaled flight data stored in the data storage unit.
It is another object of the invention to provide a system for the display of flight data derived from an aircraft flight data recorder that includes: a source of raw flight data; an interface unit effective to reformat the raw flight data; a high speed random access memory; a bulk memory; a central processing unit effective to cause the interface unit to load the reformatted raw flight data into a firs~ location in the random access memory, to convert selected portions of the raw flight data into engineering units and to store the converted flight data ~n a second locatlon in the random access memory; and a visual display unit effective to display the converted flight data stored in the second location in the random access memory.

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_ 5 BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a fllnc~ional block diagram of an aircraft flight data display systemi Fig. 2 is a functional block diagram of an interface clrcuit for use with ~he aircraft flight data display system of Fig. l; and Fig. 3 is an illustration o-f a visual display unit with an example of graphical display of flight data.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 provides an overall runctional b]ock diagram of the preferred embodiment of a system for directly displaying selected aircraft performance data from a digital flight data recorder. Aircraft perfor-mance data relating to such factors as aircraft speed, altitude, vertical acceleration, ensine pressure ratios and pitch and roll attitudes is accumulated and stored during flight in an aircraft flight data recorder indicated at 10. Some of the more recent flight data recorders such as the Sundstrand Data Control universal flight data recorder part no. 980-4100 are capable of storing twenty-five flight hours of over one hundred different flight parameters. In a digital flight data recorder such as the one indi-cated at 10, the data is typically stored in a blt serial format consisting of frames that in turn are divided into four subframes each one of which consists of sixty-four twelve bit words~ Formats o the data stored in commercial flight data recorders are de-scribed in the ARINC specifications 573 and 717 published by Aeronautical Radio, Inc., Annapolis, Maryland. Each subframe represents one second's worth of aircraft performance data. In most cases each of ~ ~ '7~'Z

the twelve bi~ words represents an aircraft flight parameter such as altitude or airspeed with ~ome parameters such as vertical acceleration being recorded several times during the one second intervals and therefore appearing in more than one word in a subframe. Similarly some types of data such as engine speeds are recorded only once in every frame or once every four seconds. The first word in each subframe consists of a sync word which both serves to mark the beainning of a subframe and to identlfy the subframe.
Currently there are two different subframe formats, depending upon the manufacture of the data accumula-tion equipment installed in the aircraft. The binary values of the ARINC 573 sync words are provided below:

FORMAT 1 FOR~AT 2 SUBFRAME Binary Value Binary Value

2 000 111 011 010 010 110 111 000

3 111 000 100 101 101 001 000 111

4 000 111 011 011 110 110 111 000 When it is desired to obtain and analyze the flight data cGntained in a flight data recorder 10, the flight data recorder 10 itself can be connected directly to a playback unit 11 that is associated with aircraft flight data display system shown in Fig. 1. However, since it i5 often impractical to remove the flight data recorder 10 from the aircraft, it ~ay be more convenient to use a copy recorder as indicated by the dash line 14 to record the data from the flight data recorder 10 on the aircraft and then connect the copy recorder 14 as indicated by line 16 to the playback unit 11. Commercially available copy recorders such as the Sundstrand Data Control copy recorder part no.
981-6024-001 are capable of record~ng over twenty-five hours of flight data in approximately thirty minutes ~21~7~

1 thereby eliminating the necessity for physically remvving the flight data recorder 10 from the aircraft.
One functi.on of the playback unit 11 is tc control the flight data recorcler 14~ For example in a digital flight data recorder the playback unit 11 can write a marker on the tape~ command the tape to run in a forward or reverse direction and sequence through the tape tracksc The playback unit 11 also serves as a preprocessor of the data on the flight data recorder 10 or copy recorder 14 by s~uarin~ and decoding biphase signals into non-return to zero signals.. Playback units are commercially available such as ~he Sundstrand Data .Control playback unit part no. 981~1218.
Connected to the playback unit 11 by means of a data l.ine 18 is an interface board 12 connected to the central processing unit 20 of a mini-computer system such as the Data General Nova Model 4S which is a sixt~en bit mini-co~puter and includes an input-output board 21. The central processing unit 20 is also connected through the I/O board 21 to a visual display unit 22 as indicated by line 24 which prefer-ably includesa color graphics terminal having a color display cathode ray tube 26 and a keyboard 28. In the preferred embodiment of the invention the cclor graphics visual display unit 22 is.the Advanced Electronic Design, Inc. AED5 12 color.graphics imaging terminal that is described in detail in the AED5 12 Usersl Manual available from Advanced Electronics Design, Inc~ of Sunnyvale, California. For some applications it may be desirable to connect a printer/
plotter 30 as indicated by line 32 to the central processing unit 20 in order to produce tabular data in printed or plotted black and white form.
Another integral portion of the aircraft flight data display system as shown in Fig. 1 is the memory ! ~ .

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arrangement which in the pxeferred embodiment includes a high speed random access memory 34 along with a lower spe~d bulk memory 36 which is preferably a disc memory: either floppy or fixed disc. As indicated in Fig. 1I the memory is connected, asrepresented by a data line 38, to the central processing unit 20 as is the bulk memory 36 indicated by the line 40. In the embodiment of the invention shown in Fig. 1 the random access memory 34 is a part of tne random access memory normally supplied with the Nova 4s computer.
The organization of the high speed random access memory ln the aircraft flight data display system includes a buffer portion 42 in a predetermined location in the random access memory 34 that is organized into a first buffer 44 and a second buffer 46. Each of the buffers 44 and 46 are organized into sixteen subframes each of which in turn are broken down into sixty-four sixteen bit wordsO In addition to the buffer memory the high speed random access memory 34 includes a set of con-version tables to aid in converting the raw aircraftperformance data from the flight data recorder 10 into data in engineering units 48, an extracted data buffer 50 for temporarlly storing selected portions of the raw aircraft performance data extracted from the buffer 42 and a converted da~a buffer 52 for temporarily storing aircraft performance data that has been con-verted and scaled into engineering units. As is conventional, the random access memory 34 also includes a predetermined location 54 for storing at least a 3 a portion of the computer program driving the central processor 20 and a location 56 for storing the computer operating system. The bulk or disc memory 36 includes a portion 58 for storing a parameter data base, a portion 60 for storing a plot data base as well as portions 62 and 64 for storing the computer program and the computer operating system.

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g In Fig. 2 is provided a detailed functional block diagram of the interface board 12 whic~ in the preferred embodiment is impl~nented on a circuit board within the computer. Bit serial flight data from the flight data recorder or the copy recorder 14 is trans-mitted over the data line 18 through the playback unit 11 and on data line 18 to a serial to parallel convexter 66. The serial to parallel converter 66 includes two 8 bit shift registers for converting the serial data received on line 18 ~o twelve bit paxallel words which then are transmitted by means of a data bus 68 to an I/O data bus transceiver 70. The serial to parallel converter also includes a data register for temporarily storing the twelve bit data word long enough so that it can be transmitted via the data bus 68 to the random access memory 34. A new twelve bit data word is latched into the data register every twelve strobe cycles which are transmitted from the playback unit 12 over a line 69. The data bus 68 is a sixteen bit parallel data bus in order to conform with the slxteen bit data system of the central processor uni~ 20 and as a result the four most sig-nificant bits of each data word applied to the bus 68 are zeroed out. As shown in Fig. 2 the I/O data bus transceiver 70 is connected to a data bus 71 ~or transmitting data to the central processing unit 2 or the high speed random access memory 34 shown in Fig. 1 via the I/O board 21. Also connected to the serial to parallel converter 66 by means of a twelve bit data bus 72 is a sync word detector 74. The sync word detector 74 includes four twelve bit data registers for holding the four sync words which are being sought as well as four comparator circuits which are effective to generate signals on a pair of lines 76 and 78 to indicate which of the four sync words have been detected. Connected to the lines 76 and 78 is a status word register 80. The status word 7i~

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register 80 is connected by means of a pair of control lines 82 and 84 to an interrupt control circuit 86.
Along with the status word register 80, a word/
bit counter circuit 88 is connected to the interrupt controller 86 by means of a pair of control lines 90 and 92 and a clock signal line 94. The word/bit counter 88 receives the strobe signal over llne 96 which represents each bit received by the serial to parallel converter 66 over the line 18 from the flight data recorder 10 or the copy recorder 14. Thus the word/bit counter 88 is effective to count the number of data bits being received by the interface board of Fig. 2 and to generate the appropriate control signals to the interrupt controller 86 along with the clock signal that increments a word counter in the word/bit counter 88. In addition the word/bit counter 88 contains a status register containing accumulated word/bit counts per subframe.
The interface board of Fig. 2 also includes a data channel controller 9~ operatively connected to the serial to parallel converter 66 by means of a control line 100 and to the central processing unit 20 by means of control lines 102 and 103.
Also included in the interface circuit of Fig.
2 is a command word register 104 that is connected either to the copy recorder 14 or the flight data recorder 10 by means of control lines 106. The command word register 104 provides a means for controlling the playback unit 11. Information is transmitted from the central processing unit 20 over the data bus 71 through the I/O data bus transceiver to the data channel controller 93 the sync word detector 74 and the command word register 104 by means of a data bus 108. It should also be pointed out that the interrupt controller 86, the status word register 80 and the data channel controller 98 are connected to the input data bus 68 along with the ~Z~'~7~7~

1 serial to parallel converter circuit 66. The serial to paralle.l conv~rter 66 and the status word register 80 are also connected hy means of colitrol llnes to the command word register 104 by control lines 110 and 112 respectively. Similarly the word~bit counter 88 is connected to the data channel controller 98 by means of a clock signal line 114 and the sync word detector 74 is connected to the interrupt controller 86 by means of a control line 119. Interrupt signals are generated by the interrupt controller 86 and transmitted directly to t.he central processing unit 20 over the control line 116c Detailed design criteria with respeot to communication of the interface boaxd 12 wi.th the preferred central processing unit is provided in the "Users' Manual - Interface Designer'~ Referencer Nova and Eclipse Line Computers" publication no.
014-000629 00 of the Data General Corporation r The process of providing a visual display of aircraft flight data from the flight data recorder 10 on the visual display unit 22 begins with the initial-ization o the interface circuit 12 by the central processing unit 20 of Fig~ 1D Under control of the central processing unit 20 resulting from the logic program stored in the program memory 54 the appropriate sync words are transmitted over the data bus 71 to the interface board of Fig~ 2 and by means of the output data bus 108 to the registers in the sync word detector 74~ A hardware word address indicated the location of the first word in the first buffer 42 in the high speed random access memory 34, where the air-craft flight data that has been converted to twelve bit words by the serial to parallel converter 66 is to be stored, is similarly transmitted over the input data bus 71. This address is stored in a register in the data channel controller 98. In order to provide ~ 2~ 37~

a data path to the central processing unit 20 and memory 34, a data channel request signal is t-rans-mitt~d from ~he data channel controller 98 on line 102 to the central processing unit 20 and acknowledged

- 5 by a signal on line 103. After the sync word detector 74 has been initialized with the appropriate sync words, a start signal is transmitted from the command word register 104 over the lines 106 to the pla~back unit 11 and then by means of a control line 117 to either the copy recorder 14 or the data recorder 10 depending on which one is connected to the playback unit 11.
When the start signal has heen received the flight data recorder 10 or the copy recorder 14 will start transmitting the flight parameter data via the playback unit 11 to the serial to parallel converter 66. At the same time, when each twelve bit parallel word is gen-erated in 66, line 114 is strobed to indicate a word has been formed. Line 102 is strobed to request access to the data channel. After data channel acknowledge signal 103 is returned from the CPU 20 the parallel word is transferred on line 68 through 70 to buffer 42.
This flight parameter data which has been converted to the twelve bit word format is transmitted by means of line 7~ to the sync word detector 74 and when any one of the four sync words has been detected by the sync word detector 74 a sync interrupt signal is generated and transmitted by means of line 119 to the in~errupt controller 86. At the same tLme the particular sync word is identified by the status word register 80 from the signals on llnes 76 and 78 which serve to identify the particular sync word found by the sync word detector.
From the information con~ained in the status word register 80 the central processing unit 20 calculates the memory address where the particular subframe of data as identified by the sync word should be stored in the buffers 44 or 46 of the high speed random access memory 34 and tha~ address is ~transrnitted to the address register in the data channel control~er 98.
For example if the first sync word detec~ed represented the third subframe the hardware memory address calcu-lated by the central processing unit 20 would be thestart of the subframe "2" as shown in buffer 44.
Once a sync word has been identified by the sync word detector 74 the interface board Fig. 2 then begins to directly transfer the synchronous raw flight param-eter data by means of the I/O data bus transceiver 70over the data bus 71 through a dedlcated data channel directly to the locations in the buffer memory 42 as indicated by the address contained in the address register in the data channel controller 98. Each time the word/bit counter 88 detects twelve bits, the clock signal is transmitted on line 114 which increments the word address in the word register of the data channel controller 98 thereby resulting in the next data word being placed in the next word of the buffer memories 42.
As each subframe in the buffer memory 42 is filled, a count of the subframes is kept by the central process-ing unit 20 in a counter 120 in the random access memory 34. When the last subframe "lS" in the second buffer 46 has been filled, the central processing unit 20 will cause the system to start writing the data in the first buffer 44 by supplying the address of the first word in that buffer to the data channel controller. In this manner only a limited amount of random access memory is required for processing the flight data. Since the flight parameter data is being automatically transmit ed directly to the buffer memory 42 ~he central processing unit 20 is free to begin to convert the raw flight parameter data containe~ in the buffer units into engineering units such as feet, kno~s or degrees for display by the visual display unit 22.

One of the primary functions of the word counter in the word/~it counter 88 is to count the number of data words received sinc the last sync word was detected by the sync word detector 74. When the count - 5 reaches 63, a clock signal generated on line 94 sig-nifies that the last data word of a subframe is about to be received. This has the effect of putting the interface board onto a sync search mode. When the next sync word is detected by the sync word detector 74 both of the bit and word counters in the word/bit counter 88 are reset to zero.
One of the functions of the word/bit counter 88 is to count the number of data bits received by the serial to parallel converter 66. In the event that 65 words have been received by the serial to parallel converter 66 and a sync word has not been detected by the sync word detector 74 an overflow signal is gen-erated in the interrupt controller 86 over line 92 causing the central processing uni~ 20 to interrupt the conversion process and to calculate a memory address for the buffer memory based on an assumption of the nature of the flight data received and where it should be stored in the buffer memory 42. This memory address is then transmitted to the address register in the data channel controller 98. In addi-tion the CPU 20 will cause error flags to be set in the buffer memory indicating that thls particular flight data being loaded in the buffer memory is questionable or may be in error. In addition the central processing unit 20 creates the appropriate reformatted sync words to be stored in the buffer memory 42 for the data that has been received without the sync word being detected by the sync word detector 74. In this manner it is possible to continue to load flight performance data in the buffer memory 42 and make it available to the display unit 22 even when a sync word has not been detected so that ~2~ 72' - 15 ~

valuable flight performance data is not lost just because there may be an error in the sync wor~
contained in ~he data.
Before the data conversion process can take place, usually during initialization of the system, the appropriate parameters and flight data units must be selected. This is usually done by an operatox utilizing the keyboard 28 of the visual display unit.
When the appropriate ~light data parameters and units have been selected, this infonmation is transmitted by the visual display unit 22 to the central procescing unit 20 which then causes the appropriate parameters from the parameter data base 58 to be transmitted fr~m the bulk memory 36 to the conversion tables 48 in the high speed random access memory 34. After the initial-ization has been completed, selected flight parameters, for example airspeed or altitude, are removed from the raw flight performance data contained in the buffer 42 and placed in the extracted data buffer 50. This process is only started after an interrupt has been generated on line 116 by interrupt controller 86 so that a full subframe is identified and stored in the first appropriate location in the first buffer 44 and it is possible to ensure that the appropriate data words from thls first subframe loaded in the buffer memory 44 are available for loading into the extracted data buffer 50. In particular after a full subframe of data has been loaded in the first buffer memory 44, the information contained in the conversion tables 48 is used to determine word location within the subframe and the data bits within the word to be accessed in order to extract the portions of the raw data which represent the selected flight parameter value. This extracted raw data is then placed in the extracted data buffer 50. The conversion of raw data to data that is scaled in the appropriate engineering units '77 occurs after all of the selected parameters have been transferred from the subframe in the buffer memory 44.
Associated with each flight parameter is a parameter code contained within the conversion tables 48 that determines the specific process for converting the raw flight data into the appropriate scaled engineering units for display on the visual display unit~
The processor 20 converts the flight parameters of interest from raw data values to engineering units by use of conversion processes keyed to the parameter type code. The conversion process proceeds with the system sequentially comparing ~he table of requested parameter types with its own t:able of possible param-eter types. When a match be~ween ~ables is found, the system branchesto apply the unique conversion process for the respective parameter type. Once the raw data is converted ~o the final engineering units value, it is stored in the converted data buffer 52 and a process for maximum/minimum limits exceedance checking, if requested during initiaiization, is performed. This procedure assigns maximum or minimum values to predefined flight parameters such as altitude or airspeed so that if these values are exceeded by the actual flight data an indication can be flashed on the CRT 26 of the visual display unit 22.
All parameters lexcluding BCD and discrete parameters) defined in the parameter data base 58 can have, along with their unique scale factor and 3Q offset, a look-up table consisting of from 2 to 40 pairs of data values and corresponding engineering units. In general/ after the offset and scale factor have been applied to the raw data value giving an intermediate engineering units result, lineax inter-polation into the look-up table is accomplished if the table exists. The general flow of the conversion process is as follows:

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raw data: offset and scale factor intermediate result: look-up ta~le final engineering units In the detailed explanation of the conversion process the following abbreviations are used:
EU - final calculated Engineering Units IR - intermediate result after one or more calculation steps Rl - raw data least significant word R2 - raw data most significant word R3 - raw data third word (pneumatic altitude conversion algorithm index) SD synchro angle in degrees FD - fine synchro angle in degrees CD coarse synchro angle in degrees Parameter type: Al (analog parameter from single data word) IR = (Rl - offset) * scale factor EU = IR : table look-up Parameter type: A2 (analog parameter from two data words) IR = (R2 * 4096) + Rl IR ~ (IR - offset) * scale factor EU = IR : table look-up 2S Parameter type: Dl (digital (signed) parameter from single data word) (sign may be from a second data word) IR = (+/-) Rl IR - ~IR - offset) * scale factor 3Q EIJ - IR : table look-up Parameter type; D2 (digital (signed) parameter from two data words) (sign must be from second data word) IR - (R2 * 4096~ + Rl IR - (~/-) IR
EU = IR : table look-up Parametex type: Xl (discrete parameter from single data word) EU = Rl Paxameter type~ X2 (discrete parame~er from two data words) EU = (R2 * 2) + Rl Parameter type: G2 (GMT coded as a BCD value in two data words) EU = HH:~M ~hours and minutes converted from BCD to ASCII characters) Parameter type: Hl (linear tHamilton Standard) synchro from single data word) SD = Rl : linear synchro converslon IR = (SD - offset) * scale factor EU = IR : table look-up Parameter type: H2 (].inear (Hamilton Standard) synchro from two data words (altitude)) CD = R2 : linear synchro conversion FD = Rl : linear synchro conversion if CD is greater than or equal to 350 degrees, then CD = CD - 360 IR = ((CD * 375) - (FD * 13.889))/5000 IR = IR : rounded to nearest integer value IR = ~FD * 13.889) + (IR * 5000) IR = (IR - offset) * scale factor EU = IR : table look-up Parameter type: Tl (.non-linear (Teledyne) synchro from single data word) SD - Rl : non-linear synchro conversion IR = (SD - offset) * scale factor EU = IR : table look-up 7 ;~

Parameter type: T2 (non linear (Teledyne) synchro from two-data words ~altitude)) CD = ~2 : non-linear synchro conversion FD = Rl : non-linear synchro conversion if CD is greater than or equal to 350 degrees, then cr) = CD - 360 IR = ((CD * 375) - (FD * 13.889)/5000 IR = IR : rounded to nearest integer value IR = (FD * 13.889) ~ (IR * 5000) IR = (IR - offset) * scale factor EU - IR : table look-up Parameter type: Pl (pneumatic parameter from single data word (UFDR pneumatic airspeed)) IR = Rl * 0.002S : voltage IR = (IR * scale factor) - offset : PSID
IR = IR * 144000 : PSFD * 1000 IR = IR : interpolated from pressure vs.
~irspeed table EU = IR : table look-up Parameter type: P3 (pneumatic parameter from three data words (UFDR pneumatic altitude)) choose conversion algorithm based upon the value of R3 (conversion algorithm index) index 0 - determine transducer calibration factors from table 0 index 1 - determine transducer calibration factors from table 1 index 2 to 7 - determine transducer calibration factors from table 0 con~ersion algorithm for index 0 to 7:

,,~" a ~i~ 6 p t- S~a TT ~ R2/10.2 : transducer temperature OT = ~ calibration factor inter~olated from indexed table by temperature TT
KT - : calibration factor interpolated from indexed table by temperature TT
- IR = (4096 - Rl) * 0.0025 IR = (IR - OT)/(0.414 * KT) IR = ~IR - offset : PSIA) IR = IR * 144000.0 : PSFA * 1000 IR - IR : interpolated from pressure vs.
altitude table EU = IR : table look~up After the flight data parameters have been scaled into the appropriate engineering units they are stored in the converted data buffer 52. The information contained within the converted data buffer 52 is then translated by the central processing unit into a format that is compatible with the particular visual display unit 22 for direct display on the cathode ray tube 26. It should also be noted that this infomration may be transmitted directly over a line 32 to tne printer/plotter 30 for tabular listing or plotting of the aircraft flight parameter data if so desired.
In Fig. 3 is provided an illustration of the sraphical output of the flight data display system.
A front view of the visual display unit 22 is shcwn with a representati~e exampie of a graphical display of flight data projected on the CRT 26. In this example four fligh~ parameters: altitude, airspeed, heading and vertical acceleration are plotted against time in seconds on the lower vertical axis 122 for an aircraft during take-off. The dashed line 124 represents aircraft altitude; the double dot line 126 represents ai.r~peed; the single dot line 128 represents magnetic heading and the solid line 130 represents vertical acceleration. Values for the flight:para~-eters are displayed on a segmented grid represented by lines 132 and 134. Since the preferred visual - 5 display unit 22 is a color graphics terminal, the various portions of the display are produced in color wherein for instance the altitude li~e 124 is yellow, the airspeed line 126 is green, ~he heading line 128 is light blue and the vertical acceleration line 130 is red with the segmented grid lines 132 and 134 in dark blue. In this particular case the display on the CRT 26 is generated one segment or pixel at a time and scrolled to the left. The central processing unit 20 will provide one second worth of data from the converted data bu~fer 52 at a tlme so that the visual display unit 22 can generate the display pixel by pixel. Then an operator by using the keyboard 28 can scroll the display on the CRT 26 to the right or the left to view the desired data.
Since the visual display unit 22 serves to both initialize and control the system by means of the key board 2~ resulting in signals transmitted to the central processing unit 20 on line 136, an operator can define the desired flight parameters and start the input of flight data from the flight data recorder 10 or copy recorder 14 into the system by using the key-board 28. In the preferred embodiment, up to eight different flight parameters along with two discretes can be displayed at any one tLme. The operator addi-tionally has the ability to control the operativecopy recorder 14 throush the keyboard ~8 by commanding it to: start, stop, select a particular track, hold or continue by means of the control functions transmitted through the central processing unit 20 and the play-back unit 11. Also, because the preferred visual display unit has a zoom capability, the operator is able to enlarge or focus in on any particular flight ~2~

parameter that he is interested in by utilizing the controls on the keyboard 28.

Claims (15)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A system for the display of flight data derived from an aircraft flight data recorded comprising:
a source of raw flight data;
an interface circuit operatively connected to said source of raw flight data effective to reformat said raw flight data;
a high speed random access memory;
a bulk memory;
a central processing unit operatively connected to said interface unit, said high speed random access mem-ory and said bulk memory, effective to cause said inter-face unit to load said reformatted raw flight data into a first predetermined location in said high speed random access memory, to convert selected portions of said refor-matted raw flight data into engineering units and to store said converted flight data in a second predetermined location in said high speed random access memory; and a visual display unit operatively connected to said central processing unit effective to display said con-verted flight data stored in said second predetermined lo-cation.

2. The system of claim 1, wherein said interface cir-cuit includes a serial to parallel converter circuit oper-atively connected to said source of flight data effective to convert bit serial data from said source of flight data into said reformatted raw flight data wherein said reformatted raw flight data is in a parallel word format.

3. The system of claim 2, wherein said interface circuit includes a counter circuit operatively connected to said serial to parallel converter circuit effective to gen-erate a signal representing the number of bits of said raw flight data received by said serial to parallel converter circuit.

4. The system of claim 3, wherein said interface cir-cuit includes a data channel controller circuit operatively connected to said counter circuit and said central process-ing unit effective to store an address of said first pre-determined location in random access memory.

5. The system of claim 4, herein said data channel controller circuit responds to said counter circuit to increment said address for each of said raw flight data words.

6. The system of claim 2, wherein said interface circuit includes a sync word detector circuit operatively connected to said serial to parallel converter circuit effective to generate a sync signal when a sync word is de-tected in said reformatted raw data.

7. The system of claim 6, wherein said interface cir-cuit includes an interrupt circuit operatively connected to said sync word detector circuit and said central processor circuit, effective to respond to said sync signal trans-mitting an interrupt signal to said central processor unit.

8. The system of claim 7, wherein said interface cir-cuit includes a counter circuit operatively connected to said serial to parallel converter circuit effective to generate a signal representing the number of bits of said raw flight data received by said serial to parallel converter circuit.

9. The system of claim 8, wherein said interface circuit includes a data channel controller circuit oper-atively connected to said counter circuit and said central processing unit effective to store an address to said first predetermined location in random access memory.

10. The system of claim 9, wherein said interrupt signal causes said central processing unit to transmit one of said addresses to said data channel controller circuit.

11. The system of claim 1, wherein said high speed random access memory includes conversion tables for use in converting said reformatted raw flight data into said converted flight data.

12. The system of claim 1, wherein said high speed random access memory includes an extracted data buffer for storing said selected portions of said reformatted raw flight data.

13. The system of claim 1, wherein said first pre-determined location includes a buffer area each of which is divided into a predetermined number of subframes.

14, The system of claim 13,wherein said high speed random access memory includes a counter and said central processor sequentially loads said reformatted raw flight data into each of said subframes, wherein said counter increments for each subframe loaded and wherein said central processing unit in response to said counter loads said re-formatted raw flight data into the first of said subframes when the last subframe has been loaded.

15. The system of claim 11,wherein said bulk memory includes a parameter data base that includes said conver-sion tables and said central processing unit is effective to load said conversion tables into said high speed random access memory in response to a signal from said visual display unit.