Does any 'heavy metal' use AoA gauges?

[phiggsbroadband]

Hi learn'ed folk, I have seen several posts that suggest the universal panacea is to place the airplane in a pitch attitude of +15 degrees.
This is all very well if your original flight path is horizontal, but not so good if the flight path is -20 degrees or more.


Surely an Angle of Attack meter would be an asset, instead of the usual AI.


Do any large airplanes have these AoA gauges?
I think they may be fitted to some smaller executive jets.
After all the wing's Cl. is determined by AoA and not by Pitch Attitude.

[Cough]

Just turn the flight path vector on. Difference between pitch attitude and flightpath = AoA...

[Green Guard]

50 ton MTOW (50,000 kg) Se210 (a Grandmother of Airbus), had AoA indicator installed in cockpit.
All daughters and grand-daughters including all cousens seem not to have it installed in cockpit.

[Denti]

It is a user option on the 737. The military customer seem to order that option, however i haven't seen it in an airline configuration yet. The space where it would be displayed on the PFD is often used for an analog RA display.

[cosmo kramer]

Just turn the flight path vector on. Difference between pitch attitude and flightpath = AoA...

Not quite... the is also angle of incidence of the wing to consider.

[gums]

Big AoA user and "indicator" advocate here.

Military likes the display because of the operational requirements and the ability to nail approach speed/AoA after a rough calculation from the book for weight and configuration and ....

We also landed closer to the "limit" than the commercial heavies, and the nasal radiators used the "indexer" lights next to gunsight/HUD for their approaches to a rolling, pitching and short runway.

The AoA is most useful when close to max performance and landing approaches. The more current indicators ( figure 1980's and on) compensate for configuration. My first jet with a good AoA indication in the HUD did not! So one rainy night I bumped the flap lever and only had leading edge flaps down and about half the basic flaps down. So my approach speed with the "correct" AoA was about 20 knots too fast and I failed to do a good cross check of configuration and the rule of thumb approach speed. Almost slid off far end of the runway.

OTOH, the basic procedures used by the heavies in the commercial world are pretty conservative and safe. "x" degrees of pitch, and "y" amount of power will work about 99.9% of the time. Unlike AF447.

For the heavies, I would recommend a HUD with an inertial-based flight path vector and the pitch lines. AoA could be optional. Nothing like seeing where you will impact the ground/runway, huh? See Asiana crash.

[Denti]

A dual HUD is standard equipment on newer aircraft like the 787 and A350 onwards. On less recent ones it is optional, like the 737, CRJ and E-Jets as well as some turboprops like the Q400. Will be interesting to see if the 777NG will switch to a similar flightdeck layout to the 787.

[NigelOnDraft]

All FBW Airbuses (A320/330/340 etc.) have an AoA display on the PFD.

Not a "standard" presentation, and not marked in units, but with 3 defined bands :ok:

More modern ones have an additional AoA display in case of loss of airspeed indication...

[ChristiaanJ]

Concorde had a combined AoA/G indicator (vertical 'tape' instrument).

[Cough]

Agree cosmo...

[AirRabbit]

Too many purchasers of airplanes (i.e., airlines ... and others) use the “expertise” of those they employ or others on their payroll in one manner or another. Often it is the additional expense of including a direct reading AOA indication, together with the “advice” provided by these “paid consultants” (some of whom don’t know their knee from their elbow and others often don’t want to “rock the boat) who generally advise that obtaining such an AOA indication would be “nice,” but it does cost more. Inevitably, a good share of these airplane purchasers decide to forego the “additional expense” since it would be merely “nice to have.” Anyone who has operationally flown airplanes with direct reading AOA indicators will tell you that it is a very cheap addition that provides a wealth of knowledge to the flight crews … but, unfortunately, the numbers of these folks is not growing and they are not usually in the chain of advisors.

[Fullblast]

Think about AF447, would have been the same outcome if the crew had an AoA indicator flashing and sounding? Who knows...

[Capt Pit Bull]

Cosmo / Cough. Depends which definition of alpha is in use (relative air flow to chord line only makes sense when considering isolated 2d airfoil sections). Often longitudinal axis to flight path is used for the whole aircraft and thus incidence is not a factor. In any event, target and limiting values can be expressed reference to either.

Plus, Cough, plenty of aircraft still around with no flight path vector.

[FE Hoppy]

PLI on ejet or even the old Avro RJ is as good as AOA. It indicates the same thing.

[Piltdown Man]

...plenty of aircraft still around with no flight path vector.

And a nearly a thousand where the thing is driven by air data. Yes, you heard correctly, from the air and the plumbing behind is like spaghetti. So a fault in one system drags down another. Worst of all, you can't get rid of the one that is lying. So when you really need it, you don't have it. Thank you Honeywell!

[underfire]

Would each aircraft, depending on loading/conditions/winds/settings, have a different AoA for the sweet spot?

[galaxy flyer]

Different airspeed, same AoA.

[misd-agin]

AOA on 737NG and 777. Customer option.


2500+ hrs looking at it.

[Check Airman]

Been in the cockpit of AA's 737,s. They have AoA gauges. Haven't seen them on their 757/767 fleet.

[underfire]

galaxy, maybe I wasnt clear..

the aircraft, at the same airspeed, will have a different AoA when heavier, than lighter...

I was also asking about landing conditions, especially weights, wont the AoA be different for the same GPA? Vref is +/-5 so there appears to be some associated AoA variable there..

I am just asking to see how many variables affect the AoA, and what is the range of the AoA as a result.

[Tu.114]

The puny little DH8-300 had something rather similar but more refined than a pure AOA indicator installed. On the left side of the horizon, there was an indication similar in looks to a GS display with a diamond. When centered, the aircraft was at 1.3 Vs = an appropriate approach speed; higher or lower speeds were shown by the diamond moving up and down.

This was a beautiful and technically rather simple fallback alternative, should the airspeed measurement give grounds for doubting its reliability. One would think that with modern EFIS aircraft this might be easily programmable and a little corner on the PFD (maybe to the left of the ASI, similar to how the VSI is often crammed beside the altimeter tape) might also be found to show this.

[roulishollandais]

HeadUpFlight.net - Principe (http://www.headupflight.net/principe/principe.htm)

[Gilles Hudicourt]

I think it's standard equipment in all Russian/Ukrainian designed Transport Aircraft.

[roulishollandais]

Mandatory informations, according to Gilbert KLOPFSTEIN :
A pilot with a perfect indicator of thrust (a myth ... that matter) should remember in all cases the necessary thrust.
If he has an indicator "push less drag" just remember that the number ... zero in all cases.

Summarize this first chapter: Flying a plane is taking him where we want, so the necessary information is the path.

The safety condition is during takeoff and landing, maintain a healthy flow around the structure, so the necessary information is the incidence. The levers adjustment must be made in accordance with the difference between the drag and the weight of component, therefore it is necessary to provide it to the pilot.

[Etud_lAvia]

At the time of the AF447 crash, because early indications were consistent with a deep stall from a condition of inoperative ASI, I was very curious whether that particular plane was fitted with an AOA indicator.

If I recall correctly, AOA is not available on the primary flight displays, but there is another screen (I want to say FMS, which I thought most unintuitive) which can be selected into a display mode that includes AOA.

I'm not a pilot myself, but it seems to me that with proper training in its use, an easy-to-read AOA display could be very helpful for:

(1) managing the ASI inoperative situation

(2) avoiding upset in general

(3) maneuvering to recover from a gross upset

[moosp]

The Tristar had one for final approach. The speed readout went to Alpha after Land Flap selection (and some other parameter, my memory fails me) so instead of chasing Vref you flew to the Alpha.

Loved it, especially in a hooligan of a wind.

[Check Airman]

The Tristar had one for final approach. The speed readout went to Alpha after Land Flap selection (and some other parameter, my memory fails me) so instead of chasing Vref you flew to the Alpha.

Loved it, especially in a hooligan of a wind.

I'm sure 411A would have loved to talk about that one, especially in light of recent accidents. Poor guy would roll over in his grave if he heard about Asiana 214...:(

[stilton]

Can you elaborate on that a bit Moosp ?


How did the airspeed display actually change ?


Very interested.

[Spooky 2]

Both American Airlines and Delta Air Lines have AOA indicators on their PFD's. 777 & 737NG. These two airlines were responsible for Boeing' making ths a customer option.

[Turbine D]

In the AF447, Thread #6, there was considerable discussions regarding unreliable air speed and AoA. There was a post by A33Zab that provided the following information regarding the Airbus BUSS design. It is standard on the A-380 and optional on other Airbus aircraft such as the A-330.

http://i1166.photobucket.com/albums/q609/DaveK72/BUSSScale_zpsf391b3dd.jpg (http://s1166.photobucket.com/user/DaveK72/media/BUSSScale_zpsf391b3dd.jpg.html)
BUSS DESIGN
The BUSS is displayed on both PFDs. It is based on Angle Of Attack (AOA) information, and
enables to easily and safely fly the aircraft without any valid airspeed indication. The BUSS
enables to fly the aircraft in the entire flight domain while observing the design limits.
The BUSS scale is divided in three color-coded areas:
• In the green area, the aircraft has normal margin towards ultimate limits i.e. VMO/VFE for
upper limit and stall for lower limit
• In the upper and lower amber areas, the aircraft has limited margin towards ultimate limits.
Flying in the amber area is acceptable for a limited period of time but it should be avoided
• The red areas (FAST or SLOW) must be avoided.
The BUSS is tuned using the aircraft’s aerodynamic model with speed brakes retracted.
When the BUSS is active:
‐ The altitude indications are based on GPS data. Two amber dashes cover the last two
digits because the GPS altitude is less accurate than the barometric altitude
‐ The vertical speed indication is no longer available.
FLYING TECHNIQUE
The PF adjusts the pitch and thrust, to maintain the AOA in the green area of the speed
scale.
For approach, the flight crew should perform a stabilized approach.
The flight crew should change the aircraft configuration with wings level.

[roulishollandais]

Turbine D
There was no BUSS on AF447 (optional)
Could you confirm BUSS is independant of ADIRU?
Why did Airbus put that AoA ref in the speed scale maintaining pilots in the idea they have to fly speed and not AoA to be stall safe? I know pilots are supposed to be stupid and often are ignorant and stupid, but they may learn ONE thing since Orvilles , Wright and Ader : that stall is not loss of speed but bad AoA.

Couldn't we definitively go to inertial HUD? Royalties?

[VNAV PATH]

BUSS is not useable above 22 or 24000 ft (thks to correct these values)

[Turbine D]

@ roulishollandais

1. I know there wasn't a BUSS installed on AF447, I just referenced the source of the photo and information I posted.

2. I attempted to provide an answer to the original question of the topic.

3. The BUSS becomes active on both PFDs when all ADRs are switched off. All ADR data is removed. The AoA signal is fed into the IR part of the ADIRU, the IR part is available even with air data off.

4. You need to converse with Airbus regarding philosophies of their BUSS design regarding speed and AoA as related to pilot intelligence levels as well as HUD displays.

@ VNAV PATH

In September 2009, Airbus sent out a notice to operators that the BUSS shouldn't be used above 25,000 feet. I am not sure of the reason behind this or if this has change in more recent times.

[BARKINGMAD]

AirRabbit has summarised it best.

It costs money to fit, if it is an option.

It would mean extra training=it costs money.

Therefore only the more enlightened fleet managers will FIGHT TOOTH & NAIL to have it provided for their troops.

Until then, be prepared for lots more CFITs by otherwise perfectly serviceable aircraft and their unwitting SLF.

"Tombstone Imperative" again, it's great book, needs reading by those in the positions of power.

[gums]

This subject has been discussed ad infinitum on the AF447 threads.

I am a big AoA proponent, but for "normal" heavy use, it is most likely not to be used for approach and such. The "simple" airspeed values from the FCOM or whatever are sufficient. IMHO.

In the case of AF447 and some other incidents, think Asiana, a reliable, inertially based flight path marker would seem to offer more info to the pilots. With a HUD, it would be even more helpful.

Just think about a display that showed your flight path starting to go down when you have been pulling back on the stick for a minute or two!!! Duhhh? Whaz happening?

So I lose all air data, including AoA, but I still have an independent doofer that shows my flight path WRT the local level and pitch lines for a few degrees above and below. Used it a time or two when the pitot-static stuff went south. No big deal, and basic attitude and throttle settings agreed with the expected flight path marker.

[mm43]

Turbine D post #30

Looks like there is an intrinsic error in the description of SLOW part of the tape, i.e.

"Red lower area corresponding to CAS > VLS"

The image below would seem to have the correct description.

http://oi43.tinypic.com/2ewjekj.jpg