Use of HUD for visual approach and landings

[Centaurus]

The accident report on the Fly Dubai B737 accident at Rostov on Don is covered in Rumours and News Forum. Elsewhere I believe the company required use of the HUD on all approaches, including visual. Certainly the captain was using HUD for the fatal go-around of the Fly Dubai 737. The report also stated that due to the captain's inappropriate use of the stabilizer trim, coupled with his apparent disorientation during the night go-around, the aircraft eventually finished up in an unusual attitude before crashing and that the HUD display followed by the pilot could have been misleading under those circumstances.

The report indicates the first officer position was not equipped with a HUD which necessarily means he would have been monitoring his own PFD during the go-around by the pilot. As recorded on the CVR, the first officer quickly picked that the captain was losing situational awareness and warned him. While I can understand the advantages of HUD in very low RVR, I wonder if operators are going too far when they make it SOP for HUD to be used on all landings regardless of visibility.

We have known for years that increased use of automation eventually leads to loss of basic instrument flying skills. Now we have companies mandating use of HUD (which is just another aspect of automation) for final approach and landing guidance in good weather. Are pilots becoming so reliant on automation they cannot be relied upon to land an aeroplane using their eyes to seek normal outside cues?

[Tomaski]

When our airline first got the 737NG, HUD use was optional unless it was specifically required for the conditions (mostly low vis app & landings). However, after a couple of tailstrike incidents, HUD use was required due to the tailstrike warning feature it incorporates. Personally, I found this to be a disconcerting requirement because 1) there are times the HUD is not particularly helpful, and 2) we can dispatch with the HUD inoperative so it's helpful to occasionally fly without it.

[PEI_3721]

The mandate to use HUD in all flight situations is misjudged, particularly for single HUD installations.

In instrument conditions using the HUD FD, the focus of attention is on the flightpath (FPA) symbol. The FD commands are relative to this, the mental model has to be referenced to where the aircraft ‘going’. This differs from conventional instrument scans (as taught in basic flying) based on an attitude referenced display (EFIS) - where the aircraft is ‘pointing’. These required different mental skills.
Normally the roll attitude is referenced to a fixed attitude symbol, but with HUD it is also shown as part of the FPA symbol, the effect of roll could move the FPA laterally (depending on mechanisation).

Head down FDs are normally referenced to attitude - ‘attitude directors’. There are exceptions; FPA on EFIS is referenced to the EFIS attitude scale, not conformal with the real world.

In visual conditions the HUD FPA can be useful by reducing the workload in assessing the aircraft flight path relative to the runway. However, landing without HUD (MEL), then the mental task could be much harder because it is not practiced in everyday use - HUD erodes this basic skill - judgement of where is the aircraft going wrt the runway.
The use of HUD in low visibility is generally an FD task or as a monitor, again different mental models and skills.

HUD adds complexity to operations, could erode basic instrument or visual assessment skills, and creates more options to be trained for and/or considered in SOPs.

[error_401]

I agree for the HUD being a very nice addition. Best use when both pilots have it I would never consider a single HUD installation.

The positive aspects are that you have all you need in your primary vision field.
Especially on the more modern aircraft with FPV featuring an acceleration cue and speed fast/slow indication.
While it is definitively a perfect tool in bumpy and ****ty weather to keep your energy where it should be.

As for downside it can be hard to interprete with it's monochromatic display. Also it's limited information on navigation does not always help situational awareness.

IMHO a very bad idea is to SOP the HUD to "always down" which makes people loose their scanning skills on a PFD. But all aircraft I know have the HUD on the MEL.
I fly about 50 % of approaches on the HUD and the others on PFD. Especially for visual approaches I like the PFD better because of the looking around. I can glance easier at the PFD then to search the focus on the HUD (the very limited position you need your eyes to be to properly see the data in the HUD). Once on final approach the HUD is just perfect to decelerate the aircraft and still fly an aiming point.

So I do consider it a tool I need to be familiar with exactly as other systems that make our lives easier. Know it, make best use of it with consideration.

[Uplinker]

I have never used a HUD.

During Airbus FBW training however, we were told never to attempt a go-around using the ‘bird’, because our brains would instinctively try to put the bird on the +15° pitch bar, (instead of the aircraft nose), and also because there is a slight delay in the bird response. So the danger was we would pull back much too much and over pitch.

Reading the final traces of the FlyDubai accident aircraft; the HUD user’s pitch control inputs were exactly opposite to the flight director pitch requests, so there was obviously huge confusion with the HUD in the heat of the moment. The monochromatic display and different symbology seem to me to be a major safety risk, given that all our flying hours have been spent looking at the familiar blue/brown ADI presentation and very little time using a HUD?

I stand to be corrected, but I cannot see an indication of engine thrust/speed on the FlyDubai HUD presentation, so this would seem to add another area of uncertainty, and a very awkward scan - from HUD to conventional instruments and back - would be required to take in the engine EPR/N1s, and flap status etc.

I can understand a HUD for military use in combat or low flying, where the pilot needs to look outside all the time, and therefore needs certain information superimposed on their outside view. But in a commercial airliner what is the advantage of a HUD? It gives the landing pilot a few extra seconds of visual accommodation in poor visibility I suppose, but does a HUD in a commercial airliner really justify its cost? I genuinely don’t know, and am asking the question.

[turbidus]

Up..I found it very useful on low vis approach up in Alaska, especially the -AR procedures. That being said, only using it on occasion is not the ideal situation.

[Centaurus]

#104 (https://www.pprune.org/10637146-post104.html) (permalink (https://www.pprune.org/rumours-news/627546-flydubai-crash-rvi-final-report-out-6.html#post10637146))

Circa 1982 I watched an MD83 belonging to Peter Conrad land at Nauru island in the Central Pacific. The name on the fuselage was Friendship 83 and it was on an around the world trip to sell MD 83's.
The runway on Nauru in those days was 5600 ft long and no over-run safety areas.
The aircraft came over the fence very high compared to how we flew the Boeing 737-200 of Air Nauru where we used the T-VASIS. I thought it would surely overrun as it touched down a long way in. Maximum braking saved it that day. Later we talked to the captain who said he used the HUD for all landings.

After watching with increasing alarm at the high flare, long float and deep landing, I thought it was the height of poor airmanship to use a HUD on a sunny day visual approach instead of normal eye sight judgement coupled with T-VASIS slope guidance that we used in the old 737-200's.

[vilas]

The problem started with application of GA thrust because the aircraft was light the nose pitched up which had the PF was pushing forward on the yoke with varying erratic attitude. After some time he used electric trim for 12 seconds. I was wondering if the pilot was flying without using the arm rest then the reference of the resting hand position is lost and such erratic inputs are possible.

[jmmoric]

#104 (https://www.pprune.org/10637146-post104.html) (permalink (https://www.pprune.org/rumours-news/627546-flydubai-crash-rvi-final-report-out-6.html#post10637146))Circa 1982...
Is it really that long ago HUD's were installed in commercial jets?

[Centaurus]

The modern HUD used in instrument flight rules (https://en.wikipedia.org/wiki/Instrument_flight_rules) approaches to landing was developed in 1975

Jmmoric. I Googled your question and received the above answer. Cent.

[Judd]

I was wondering if the pilot was flying without using the arm rest then the reference of the resting hand position is lost and such erratic inputs are possible.
The arm rests are not there to help with instrument flying otherwise they would be a no-go item. Some pilots use them while others prefer not to

Use of arm rests are very much a personal choice although it is not uncommon to have check captains insist the PF use them if pilot is hand flying. That can be exceedingly annoying.

[vilas]

The arm rests are not there to help with instrument flying otherwise they would be a no-go item. Some pilots use them while others prefer not to

Use of arm rests are very much a personal choice although it is not uncommon to have check captains insist the PF use them if pilot is hand flying. That can be exceedingly annoying.
It is a personal choice but in tricky situation it can lead to excessive inputs as it happened here because the reference position of arm is lost. The erratic pitch inputs followed by a steep dive by the PF in this case defy any logic. We are trying to guess the reason. Not using arm rest could be one. In Airbus it is taught to use it and how to adjust arm rest and seat is carefully explained. It is an MEL item. If affected crew member doesn't accept it is a NO GO.

[Judd]

Point taken, Vilas. Using a side stick controller I can understand how the arm rest would help.

[excrab]

It is a personal choice but in tricky situation it can lead to excessive inputs as it happened here because the reference position of arm is lost. The erratic pitch inputs followed by a steep dive by the PF in this case defy any logic. We are trying to guess the reason. Not using arm rest could be one. In Airbus it is taught to use it and how to adjust arm rest and seat is carefully explained. It is an MEL item. If affected crew member doesn't accept it is a NO GO.

It was a Boeing, not an Airbus. The control yoke gives feedback, unlike (I believe), the computer sidestick in an Airbus. Because of this you don’t need to fly with armrests in a set position, or at all. The crash may have happened in part due to fatigue, in part due to poor training, in part due to confusion with the HUD display, in part due to disorientation. It can probably be guaranteed that they didn’t dive into the ground at 300 kits because the PF wasn’t using the armrests.

[gums]

Salute!

I first flew with an inertial system that portrayed the flight path vector in 1971. It was a Marconi HUD in the A-7D, and was a delight to use along with the steam gauges. For instrument flying it was a great crosscheck, and helped a lot at the end game. USAF directives were clear that our HUD was not to be the primary instrument when in IMC. But I gotta tellya that I used it more than the steam gauges because it told me where I was headed, but it did not have vertical guidance except in our terrain following mode.

Flying a precision approach was a piece of cake because we could place the FPV on the appropriate pitch line and keep on the glide path easily. Only thing we used the FPV on a go around was to crosscheck our other gauges that lagged actual flight path, and give us a good feeling. Ask any Navy dude about taking off on a dark night from the boat, and the good feeling that you were not descending into the drink.

I am mystified by the Dubai AC actions that appear to be trying to follow some command on the HUD versus using it to affirm a positive rate of climb that was also indicated on the steam gauges. And speaking of that..... I had a static port freeze one day during the descent from holding to the non-precision minimum altitude. That FPV was comforting, along with a radar altimeter. So set power per normal for configuration and don't put that inertial doofer below a normal descent angle.

Gums sends...

P.S. I think the AF 447 folks would have realized that they were stalled when the FPV started down when the attitude was still nose high! Duh...

[Icelanta]

If you teach your crew to always use HUD and/or flight director, mandate maximum use of autopilot and forbid them to fly raw-data, you are simply asking to have a crash.
I can only recommend those I care about to please avoid airlines where raw-data flying is forbidden.

[vilas]

P.S. I think the AF 447 folks would have realized that they were stalled when the FPV started down when the attitude was still nose high! Duh... I don't think anything would have changed the AF447 outcome because they didn't figure out the problem and even if they did were ill equipped to deal with it. Even to notice FPV one has to look at PFD which none of them did otherwise even without FPV they would have seen the high attitude and corrected it nor did they hear the stall warning.

[Fursty Ferret]

I don't think anything would have changed the AF447 outcome because they didn't figure out the problem and even if they did were ill equipped to deal with it. Even to notice FPV one has to look at PFD which none of them did otherwise even without FPV they would have seen the high attitude and corrected it nor did they hear the stall warning.

Yeah, given they ignored the "STALL, STALL" call-out I think we can safely say they wouldn't have noticed the FPV disappearing off the bottom of a HUD.