Loads of info about the LCA

Got this from BR’s LCA section

LCA : MAN-MACHINE INTERFACE AND FLIGHT SAFETY
Wg Cdr Rajiv Kothiyal KC (Retd)
Experimental Test Pilot
Ph: xxxxxx, E-mail: [email]xxxxx@xxxx.xxx[/email]
ABSTRACT
1. Almost two years after the first flight of the LCA on 04 Jan 2001 the LCA
flight test programme is well under way with flights flown successfully at
regular intervals. This paper, however, deals with the preparations prior to
the first flight of LCA TD-1. The paper specifically addresses Man Machine
Interface issues and their effect on Flight Safety during the period leading
up to the first flight of LCA.
INTRODUCTION
2. After the first flight of LCA TD-1 on 04 Jan 2001, the LCA flight test
programme is proceeding smoothly with a total of 44 flights completed
successfully by mid December 2002. The credit for the success of the
flights goes to the combined and dedicated efforts put in by Team LCA.
3. The LCA is a state-of-the-art fighter. However, to appreciate the
significance of LCA’s design and development and the challenges of flight
testing it, one should first be aware of the historical background of the
fighter aircraft industry in India. The last indigenously designed fighter
prototype, the HF-24 ‘Marut’ first flew way back in1961. Though the aircraft
served the IAF between 1966-1983, no fighter aircraft design and
development was undertaken after the HF-24. The industry had only been
undertaking licensed production of proven designs such as the MIG-21,
MIG-27, Jaguar etc. Thus the design, development and flight testing
capabilities suffered for want of a worthwhile aircraft programme. It took
nearly four decades before the next fighter prototype, LCA TD-1, took to the
skies. LCA is packed with the latest technologies in terms of Quadraplex
Digital Flight Control system, Glass Cockpit, Microprocessor based
management of Utility system and use of composites. Almost all of these
technologies were incorporated directly into the LCA without first proving
them in a research/ test bed airborne platform. In the history of aviation, it is
unlikely that there would be another example of a prototype packed with so
many new technologies. The LCA differs from other prototypes undertaken
in this country not only in terms of technology, but also in management and
risk-levels. This paper deals with the aspect of managing risk levels by the
flight test group in the LCA in terms of Man Machine Interface issues and
their effect on Flight Safety.
MAN-MACHINE INTERFACE (MMI)
4. Man-Machine Interface (MMI) is the process which facilitates harmonious
and efficient interaction of the man with the machine. In an aircraft prototype
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this interface would mainly be between the technicians and the aircraft and
between pilots and the aircraft. This paper deals with the man-machine
interface between pilots and the aircraft.
5. A large number of MMI issues cropped up during the design and
development phase of the LCA. Some of these issues were identified by
the designers, some by the certification agencies and some by the flight test
group. Majority of these MMI issues had flight safety connotations and
therefore had to be resolved. Most of these issues were identified in the test
rigs but still there were some which could be observed only when testing
commenced in the actual aircraft. Such late identification of MMI issues
invariably led to slippages in the programme schedules.
MMI AND FLIGHT SAFETY
6. The flight test group, comprising test pilots and engineers, addressed MMI
issues throughout the design and development phase of the LCA. In the
phase leading upto the first flight MMI issues which impacted flight safety
were dealt on priority while other MMI issues were documented for action
during the subsequent software/hardware upgrade. The bottom line for
the first flight was safety. The LCA had to get airborne safely, fly around
safely and, most important of all, land safely. The flight test group was
aware that performance evaluation was important but this could be
addressed in subsequent flights once it was assured that LCA and its
systems behaved as predicted during the first flight. The dictum for the
test pilot was to be prepared to handle the worst possible contingency and
still be able to recover the aircraft safely back to base. It did not matter
how many redundancies had been built into each system. As far as the
flight test group was concerned, they had to assume the worst possible
failure and have their solution ready in case such an eventuality arose.
7. During the early stages of the development the designers had, to the best
of their understanding, attempted to address pilot related MMI issues.
However, only a specialist user could unearth the latent issues. Therefore,
during their interaction with the designers and during tests on the rigs and
on the actual aircraft the flight test group discovered a number of MMI
issues which had to be resolved prior to the first flight. This paper
discusses in detail some of these issues and the manner in which they
were resolved.
EXAMPLES OF MMI ISSUES
Warning List Page on RMFD
8. Status: Failure warning philosophy on LCA. There were three display
surfaces on the LCA- the Head Up Display (HUD), the Left Multi Function
Display (LMFD) and the Right Multi Function Display (RMFD) (Fig1).The
HUD displayed navigation and weapon attack symbology and allowed the
pilot to monitor all essential parameters without the need to look inside the
cockpit. The two MFDs had a set of buttons around them which were used
to view pages displaying information relating to navigation, attitude,
aircraft systems, radar etc. Incase of a system failure a warning box was
Proceedings of Aero India 2003 2
displayed on all three display surfaces and the failure along with critical
pilot actions was indicated inside the box in textural form. For example, let
us consider failure of Electrical Generator 2 System. The warning box
would display ‘GEN 2 FAIL’ and below that critical pilot actions of ‘Reset :
Land ASAP’ (Fig 2). Once the pilot’s attention was drawn to the existing
failure his next action was to depress a button an the throttle. This action
erased the warning box from all the displays and simultaneously the
RMFD displayed the relevant system page while the LMFD displayed the
list of pilot actions (Fig 3). The system page was a line diagram of the
system with affected sub-systems depicted in red/amber colour. The pilot
could go back to the original MFD pages, which were displayed prior to
the failure, by making appropriate selections on the MFDs. If more than
one failure were to occur, the letters ‘MW’ was displayed next to the
warning box to alert the pilot (Fig 4). In such a scenario the failure with the
highest priority was displayed first. After clearing the first warning the pilot
had to use the button on the throttle again in a similar manner for the
subsequent failures. A Cockpit Environment Facility (CEF) had been set
up in ADA to help the test pilots identify MMI issues related to the
information available to the pilot in the cockpit.
9. The Problem: During the evaluation of the warning philosophy in the CEF
the test pilots identified the following as flight safety related MMI issues:
a. There was no comprehensive list in the cockpit indicating the failures
existing in the aircraft at any given time.
b. Lack of such information led to poor situational awareness in the
cockpit.
c. There was no facility to recall the pilot actions on LMFD in case the
actions had to be executed after a time delay.
d. The failure warning procedure increased pilot workload
e. The procedure could deny crucial information to the pilot during time
critical phases of flight such as take off, landing and operational tasks.
10. Solution: This MMI problem was identified as a Flight Safety issue by the
flight test group and therefore had to be resolved prior to the first flight.
The solution was worked out between the test pilots and the designers.
(i) The first cut solution was initially evaluated in the CEF. Iterative
process was used to arrive at the final solution.
(ii) The existing software in the Display Processor was modified.
(iii) A ‘W LIST’ selection was provided on the RMFD. The pilot had to
depress this button to view all the existing failures listed on basis of a
pre-defined priority (Fig 5). If a failure rectified on its own accord then it
was automatically removed from the list. The W LIST facility provided
the pilot with better awareness of the health of the aircraft systems.
(iv) A cursor and scroll facility was also provided which allowed the pilot
to select any of the listed failures for displaying the associated pilot
actions on the LMFD.
Proceedings of Aero India 2003 3
NON AVAILABILITY OF NEUTRAL TRIM INDICATION
11.
12.
.
13.
HIGH TOE PEDAL FORCES
14.
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(v) A ‘Long Press’ facility was provided in the warning erase button on
the throttle. Keeping the button depressed for more than 1.5 seconds
erased all the failure warnings from the displays and sent them to the
memory while the MFDs retained the previously selected pages. This
facility was very useful in situations where monitoring of current MFD
pages was essential or when the pilot did not want to be distracted by
lower priority failure warnings. Such situations could arise during takeoff,
landing or operational task such as radar tracking, firing of
weapons etc.
Status. The LCA has two sets of elevons- outboards and inboards. Upon
initialization of the Fight Control System (FCS) after engine startup these
elevons were supposed to be in the neutral position. However, no
indication was provided in the LCA cockpit to indicate to the pilot that the
elevons were indeed in the desired position prior to take-off. Further, on
ground, if the pilot were to inadvertently move the elevon trim switch
located in the pilots handgrip, it was not possible for him to reacquire the
Neutral Trim state without invoking the FCS built- in -test process all over
again.
Problem. The absence of a Neutral Trim indicator was considered a
Flight Safety related MMI issue in the take-off phase by the flight test
group. If, due to any reason, the elevons were displaced up or down from
the desired neutral position then it would lead to unpredictable handling
qualities during the nose rotation and lift off. These conditions were
evaluated in the Real Time Simulator (RTS) at ADE and it was concluded
that, depending on the degree of elevon offset from neutral ,the execution
of the take off procedure could result in an unacceptable situation.
Solution. Interaction with the designers revealed that it was not possible
to provide a Trim Neutral indication in the cockpit without seriously
impacting programme schedules. Therefore, the only option was to find a
procedural solution.
i. The pilots were not to operate the Trim switch at any time once the
FCS BITs were completed.
ii. The technicians responsible for seeing-off the aircraft had to
physically verify that the elevons were in the neutral position.
iii. Elevon actuator ramp position was displayed in the Telemetry
Room. It was the Test Director’s responsibility to confirm neutral
status of the elevons to the pilot prior to the take-off roll.
Status. Deceleration in the LCA was achieved by the application of
pressure on the foot pedals. In the early stages of the development
phase, just prior to the Low Speed Taxi trials, it was observed by the flight
test group that the Toe Pedal Forces were higher than desired.
15.
16.
RTS EVALUATION OF CONTROL LAWS
17.
18.
19.
Proceedings of Aero India 2003 5
Problem. One of the main objectives of the Low Speed Taxi trials was to
assess the efficacy of the digital braking system. The test schedules were,
therefore, planned to evaluate the different modes of braking throughout
the taxiing. This implied that the pilot would be applying the toe brake
pedals during almost the entire 30-40 minutes of the tests. Continuous
application of high toe pedal forces would lead to pilot fatigue which
obviously would adversely impact Flight Safety. Thus the flight test group
categorised high toe pedal forces as a Flight Safety related MMI issue.
Solution. The easiest solution to this MMI problem would have been to
remove the pedal assembly from the aircraft, modify it and re-install it.
However, this process would have entailed slippages in the programme
schedule which at that point in time were considered undesirable. The
flight test groups prime responsibility was ensuring Flight Safety.
However, being part of the LCA team, they also had to consider
programme objectives without compromising Flight Safety. To achieve
these combined goals a risk-assessment analysis was carried out
alongwith the designers and certification agencies. The factors
considered were : the test schedule limited speed of 75 kmph and the
availability of hand operated parking brakes as a last resort for
decelerating the aircraft in the event of failure of both main and standby
brakes or in the event of pilot fatigue. Based on the above it was decided
that the situation could be handled in the worst possible scenario. Thus
the Low Speed Taxi trials were carried out and all the taxi tests went off
smoothly. Of course, once the Low Speed Taxi runs were completed the
pedal assembly was removed, the application forces were modified and,
after obtaining clearance from the test pilots, it was re-installed in the
LCA. No problem concerning toe pedal forces was faced thereafter in
either the High Speed Taxi trials or the subsequent flights.
RTS. The Real Time Simulator (RTS) at ADE, Bangalore, was utilised by
the test pilots for assessing the Handling Qualities (HQ) of the FCS
Control Laws ( CLAW).The HQ were assessed in the normal mode of
the CLAW as well as in the failure modes. Evaluation of the failure modes
was essential so that the test pilots could get a feel of the degraded
handling qualities of the aircraft and evolve piloting procedures to handle
the situation. A couple of Flight Safety related MMI findings in the RTS are
discussed below :
Finding. During the failure mode evaluation it was observed that, with
inboard elevons failed and the landing gear lever selected up, the aircraft
would depart in pitch at speeds below 300 kmph. With outboard elevons
failed and the landing gear lever selected up, the aircraft departed in pitch
at speeds below 380 kmph. The landing gear lever position basically
dictated the FCS gains changeover between landing gear down and
landing gear up gains in the control law.
Solution. Pilot procedures were evolved through RTS exercises. It was
decided that, after take-off or after go-around from approach, the landing
gear would be selected up only above a speed of 400 kmph. During
approach or whenever the test schedule demanded it, the landing gear
would be lowered above a speed of 380 kmph. This procedure would
ensure that the aircraft remained in control of the pilot even with a failed
pair of elevons. This procedure effectively put a lot of pressure on the
pilots since it drastically reduced the speed envelope for landing gear
operation. The minimum speed for lowering the gear was now increased
due to the newly evolved pilot procedure while the maximum speed with
the gear down was already restricted due structural considerations.
20. Finding. During landing assessment in the RTS with outboard elevons
failed and a 20 knots cross-wind, it was observed that when the nose was
straightened after flare-out the aircraft would depart in roll. However, at 10
knots cross-wind the aircraft was controllable in similar conditions.
21. Solution. Pilot procedures were evolved through RTS exercises. It was
decided that if strong winds were reported for landing, the pilot would kick
off approximately only half the drift after flare-out. This meant that the
landing gear would impact the runway with an offset. Therefore, its
structural ability to bear the resulting side-loads had to be ascertained.
This exercise was carried out by the Structures group and it was
confirmed that the side loads experienced in such a situation would be
within acceptable limits.
FORMULATION OF PILOT EMERGENCY PROCEDURES
22. Status. In the early stages of the development phase the flight test group
found that the pilot actions for failure states were stipulated as either ‘Land
ASAP ‘ or ‘ Throttle back Land ASAP’ .The pilots would have been delighted
if indeed such had been the case! It would have solved their problem of
committing to memory complicated pilot actions and would have reduced
their workload during failure conditions. However, it was not so simple—
nothing ever is in a prototype aircraft programme.
23. Solution. The flight test group held extensive interactive sessions with
the designers. Detailed pilot actions for each failure were formulated
system-wise. Issue 1 of such comprehensive pilot actions was released in
1997. With each new input from the design groups the actions were
updated and the next version released. Finally in 2000 a booklet was
prepared by ADA which combined the normal pilot procedures and the pilot
actions for each failure state. The pilot actions for each failure were then
ported onto the Display Processor (DP) to be displayed on the LMFD as per
the requirements. However, the FCS failure state pilot actions could not be
ported onto the DP as they could not be finalised within the specified time
schedule. Rather than delay the release of the modified DP software it was
decided that the FCS failure pilot actions would only be available in the pilot
booklet kept in the cockpit. The pilots were also required to commit to
memory the pilot actions for FCS failures as well as some of the other
critical failures.
CONCLUSION
24. As is evident from the above examples, Man Machine Interface and Flight
Safety are key areas in the development stage of a prototype aircraft. There
were innumerable other MMI issues which were identified and resolved during
the design and development of the LCA. Addressing MMI and Flight Safety
issues is not something which one does overnight. The involvement of the
Proceedings of Aero India 2003 6
designers and the flight test group at every stage of the project is essential for
timely detection of such issues. Please note that the keyword here is ‘timely’.
Late identification of such issues would obviously impact programme
schedules and costs. Many of the MMI issues surfaced when the pilots and
engineers involved themselves in system testing in the rigs. A large number
of flight safety related MMI issues were discovered during assessment of
failure states in the test rigs and simulators. Therefore, failure states testing of
each system on the test rigs must be an integral part of the developmental
process.
25. It should be understood by all that flight of a prototype aircraft can never be
guaranteed as risk-free. However, our aim as designers, certification
agencies and flight test personnel should be to resolve all known and
potential Flight Safety related MMI issues prior to the flight. This is the bottom
line. It is as applicable to the first flight as it is applicable to the last flight in the
developmental programme of a prototype aeroplane.
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THE THREE DISPLAY SURFACES
FIG – I
WARNING BOX ON DISPLAYS
FIG – 2
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PILOT ACTIONS & SYSTEM PAGE ON MFDs
FIG – 3
FIG-4
MULTIPLE FAILURE WARNING ON DISPLAYS
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FIG-5
WARNING LIST PAGE ON RMFD
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Bio-Data
NAME: Wg Cdr Rajiv kothiyal, KC (Retd)
AGE: 44 Yrs
I was born on 11 Sep 1958 at Dehra dun. My father was a private practitioner at Dehra
dun. I did my entire schooling at Cambrian hall, Dehra dun and appeared for the ISC
exam in 1974. I entered the National Defence Academy as an air force cadet in 1978
and graduated with a B.Sc degree in 1978. I earned my wings and was commissioned in
the flying branch of the IAF on 15 Jun 1979. The first six years of service were spent in
operational fighter squadrons where I was declared full operational on MIG-21 Bis
aircraft. I underwent the flying instructors course at the Flying instructors school (FIS)
Tambaram, chennai and graduated as a Qualified Flying instructor (QFI).
After an instructional tenure at the IAF flight training academy at Bidar, where I upgraded
my instructional category to A2 , I was posted to a MIG-29 Squadron in 1987. In 1989, I
was selected to undergo an Experimental tests Pilots course at the United States Air
Force Tests Pilots School at Edwards Air Force base, California, USA. Since my return I
have done a tenure as a test pilot at the IAF flight test centre (Aircraft and System
Testing Establishment) at Bangalore. Before joining the LCA project in 1995, I was in a
MIG-29 squadron and also graduated from the Defence Services Staff College at
Wellington. I worked in the LCA project from Feb 1995 to Dec 2001.After completing my
tenure at ADA, I was posted back to the regular Air force. I was granted premature
retirement from the IAF on 15 Aug 02.
On 26th Jan 2001, the Rashtrapati honoured me with the award of KIRTI CHAKRA for
my contribution to the LCA programme and the successful maiden flight.
On 29th Sep 2001, I was awarded the international Iven C Kincheloe trophy in Los
Angeles, USA, FOR Best Professional Achievement in Flight Testing, 2000-2001 by the
Society of Experimental Test Pilots, California, USA.
Proceedings of Aero India 2003 11