khaosai

Hi,

Stick shaker speed will vary depending on the g loading. Bank angle and load factor will affect these. Remember you can stall an aircraft in any attitude and sometimes it's not immediately obvious.

Flap manoeuvre speeds are a function of aircraft weight, thus the heavier you are for landing the faster your approach and subsequent landing speed will be. On the primary flight display you have the flap up indication followed by the flap 1, 5, 15/20 and flap 30 which is generally used for landing. Flap 25 can also be used for landing but is not used that often.

Lets take a Boeing 777-200ER landing at a sea level airport at 200 tons using flaps 30. The velocity reference speed (VREF) will be 135 knots. That would then indicate to the crew how slowly they could fly with no flap selected and when they would have to select flaps to allow a speed reduction. The calculation is based on VREF30 plus 80 knots. So minimum clean speed would be 215 knots reducing by 20 knots per the next stage of flap selected, I.e select flaps 1 and reduce speed to 195 knots.

When flying at the appropriate speed for the flap setting you basically have full manoeuvre margin.

Also on the airspeed indication you have an amber band. The top of the amber band is minimum manoeuvre speed and is based on angle of attack and speed so is constantly changing during the flight. When you get approximately halfway into the amber band you will get an airspeed low caution.

At the bottom of the amber band you have a striped red and black brick type indication which is where you stop flying. The aircraft will be stalled if the speed is in this area.

The stick shaker indication to the crew will occur just before the speed reaches this area.

Hi TallGuyJohn, it does get a little technical so apologies for that.

This aircraft can be flown perfectly well with the auto throttle armed and engaged or armed and disengaged or even disarmed and therefore not engaged.

It comes down to awareness, proficiency, an understanding of the equipment you are operation/flying and never loose sight of the big picture. It's just another aircraft at the end of the day so the basics of pitch and power still apply.

Aim at the desired gear touchdown point, not the threshold but about 300 metres further down the runway which is indicated by they runway markings and generally are at the same point where the PAPI light indications are at. Some small corrections may be required until the selected point remains stationary in the pilots field of view and small changes necessary in thrust to control speed. These aircraft have the main wheels a considerable distance behind the pilot so you don't want to get low during the approach. You will aim to cross the runway threshold at 50 feet which will ensure the gear clearance and will also result in an accurate touch down.

Will be interested to see the final report.

Hi,

F430murci, yeas the auto throttles do work below 500ft on this aircraft. We generally use the auto throttle from the start of take off when we press the take off switch until after touchdown and reverse thrust is selected which causes the auto throttle to disconnect.

The glare shield panel is where the mode control panel (MCP) is and which contains the auto throttle switches. There are two switches, one for the left throttle and one for the right throttle. When selected up they are armed and when selected down they are off.

In the armed mode the auto throttle will activate when vertical navigation (VNAV), flight level change (FLCH) or take off/ go around (TOGA) switch is pushed. It will also activate when the speed switch is pushed and the pitch mode is altitude (ALT), vertical speed (VS) or glide slope (G/S).

When selected off it disconnects the selected auto throttle, I.e. left or right or both and thus prevents the selected auto throttle activating. These switches are generally never selected off unless directed to do so, perhaps due to being unserviceable where the crew will follow the guidance in the minimum equipment list (MEL). Another reason for selecting them off is if a non normal checklist or memory item dictates so, I.e engine failure.

On the actual thrust levers you have auto throttle disconnect switches. Pushing this switch disconnects both auto throttles and as a result gives you an amber master caution light and aural sound. It also gives you a message on you engine indication crew alerting system (EICAS) which large upper screen located between both pilots. They are still in the armed position based on switch selection on the MCP.

Now the potential threats. If descending in FLCH the auto throttle (A/T) will be in HOLD mode until the altitude selected is reached when it would then change to speed (SPD). If you have selected zero in the altitude window then you can see the end result. It's very unlikely that a crew would do such a thing, but not impossible.

In HOLD mode the auto throttle servos are inhibited but the pilot can move them manually as required.

The auto throttle can support stall protection when armed but not activated, i.e having disconnected them using the switches on the thrust lever. If the speed gets close to stick shaker activation the the auto throttle engages and thrust will increase to maintain minimum manoeuvre speed which is indicated by the top of the amber band located on the primary flight display (PFD) speed indication.

Depending on the phase of flight vertical navigation speed (VNAV SPD) could be in IDLE or HOLD. With HOLD annunciated you do not get any stall protection. If FLCH is the pitch mode then you do not get stall protection. When below 100ft you do not get any stall protection.

The system logic allows the aircraft to be manually flown with the thrust levers engaged. So basically you can be looking out the window on a visual approach with no autopilot and the flight director guidance off. It may be in hold mode so you will have to set the required thrust. If the flight director is off the auto throttle will retard to idle at 25ft radio altitude (RA). So if substantially low over water the thrust lever would retard as you are getting radio altitude indications from the surface of the sea.

I am all for discussion, speculation information etc. The facts will soon become clear. Human factors played a huge part in this accident and will be discussed in recurrent training within airlines for decades to come.

Hi jpinx,

your right that the cultural aspect may have played a part here. Its a very hierarchical society, particularly if one has had an illustrious career in the military which may or not have been the case here. The cockpit voice recorder makes for interesting listening I am sure.

Maybe some of the pilot-aware members here can post on the proper role for an instructor pilot in this kind of situation:

You're on a real commercial flight, fully loaded with passengers, the training pilot has the controls and is coming in for a landing. But as you're approaching the landing, you realize the training pilot is significantly off the mark.

What is the instructor pilot supposed to do in that kind of situation? Verbally instruct the training pilot to make the necessary changes? Or, if the instructor pilot thinks things have gotten out of control, take over the controls himself and try to right the aircraft?

As an instructor sitting in an operation seat, I.e. front left or right seat then you assume the role of commander, and therefore full responsibility for the safety of the flight. All crew have a shared responsibilty for safety but the Operating Captain has overall responsibility. As this seems to be a Captain transitioning from one aircraft type to another then it's important to let him make command decisions until such time that safety becomes compromised.

As part of an instructor course you will be given some guidance on how to train as well as check, and at what stage you should intervene. Now you would probably start with some form of verbal intervention. On occasion you have to take over control, manual intervention. It's important to not let a situation develop that will compromise the safety or the commercial aspect of the job.

Early manual intervention in this case would have prevented this situation and resulted in a go around so safety would not be compromised. However taking the commercial case, verbal intervention at a much earlier stage during descent and approach would have been far more effective. The approach would not have been unstable and would have probably resulted in a normal approach and landing.

The job is very dynamic, things are changing by the second and decisions need to be made soundly and correctly. During a normal sort of approach speed this aircraft is travelling close to one aircraft length per second. So paying attention and operating the aircraft accurately are very important.

It all comes down to being assertive in a flight deck. If things are not going how they should then you need to speak up, regardless if your the 200 hour new first officer or the experienced 20000 hour examiner.

Hi,

The transition requires hard work on the trainees part, it can be demanding, but it is not particularly difficult. You will learn the technical side of the aircraft in a classroom environment and from there progress to simulator training where you get to learn the skills required to operate the aircraft in a safe manner. Once you have reached the expected standard and completed a check then will you go on to the actual aircraft and carry out line training. That also culminates in a check prior to being released to fly as part of a crew.

People learn and develop at different rates and as a result some people may require additional training. If additional training is required it will generally be offered to the student.

The 777 simulators that pilots use to train in accurately represent how the real aircraft flies and handles.

The B777 is a fantastic aircraft to operate. It flies in a very similar manner to the other large Boeing EFIS aircraft. The automation is very user friendly. It flies well, has lots of performance available and without a doubt makes money for the airlines that fly them.

This has all the hallmarks of a rushed approach which became unstable and should have resulted in a go around. This airline, like most will have specific stabilisation requirements that need to be met and maintained for the approach to continue. Parameters such as rate of descent, becoming too fast or too slow, aircraft configuration etc will have to be met prior to reaching a certain point on the approach.

SFO is not an overly demanding airport to fly into so long as you have carried out a briefing highlighting specific threats. For a crew visiting an airport for the first time those threats should be documented and should be made readily available to the crew to peruse at any time.

Hi,

Seems the answer might be with the auto throttle flight mode annunciation. There are some traps for the unwary with the B777 system that may prevent the auto throttle wake up function from engaging in certain situations. With the auto throttle engaged in FLCH or when below 100ft on approach you do not get stall protection. If descending in VNAV SPD and HOLD annunciates you will not get stall protection.

They may well have got a sink rate caution if excessive descent rate was sensed and an airspeed low caution if below minimum manoeuvre speed.

The recommended technique on the B777 is to leave the auto throttle engaged during approach and landing, even whilst manually flying the aircraft. The technique on the B747 is slightly different where you would disconnect the auto throttle whilst manually flying the aircraft.

With regards to the communication being possible on the ground with no engines or APU, the aircraft battery will provide power to the emergency lighting and the Captains control display unit which contains the aircraft radios.

Line training with full fare paying passengers onboard is a common feature in airline flying. It's taken very seriously, with the actual training taking a very distant third behind the safety and commercial aspects of the job.

Hi,

Fair comment regarding weight, truth be told I don't know what the actual weight was. It was more of an idea of approach speeds versus rate of descent. Lets assume it was 30 tons lighter then. Approx 10kts less speed on approach the required descent rate would be in the region of 650ft per minute.

It's not however uncommon to fly long distances on large aircraft and land at or close to max landing weight.

Hi,

Unstable approaches are a huge threat to the industry. Most airlines have a published stabilisation criteria. Speed, descent rate, power setting etc.

This approach at max landing weight would have required a descent rate of approx 700ft per minute. If you have started off high then it's a challenge as time is compressed the closer you get to the runway. Boeing commonly refer to the safest course of action in their documentation, so possibly in this case a go around would have been a more appropriate decision to make.

I would rather comment on digital flight data information than the info you have provided, however it could well give some clues to the end result.

Hi,

Lots of speculation which is understandable, and normal behaviour for people to come up with some theories to what caused the crash.

Depth perception landing on water would be a challenge. This is slightly different where you have a long runway as your primary focus. Large aircraft don't use the threshold as an aiming point. What you use is the touchdown zone markings at the 300 metre point on the runway. When on profile you will cross the threshold at approx 50ft and commence the flare between 20 and 30ft on the B777.

A normal approach will generally have some sort of glide slope guidance, be it accurately using the instrument landing system, RNAV approach or perhaps an approach that gives you a height check against a certain distance from touchdown. This was a visual approach conducted in nice weather that has gone badly wrong during the final stages of the approach. The aircraft has hit the wall approx 500 metres prior to the required touchdown point. The aircraft is capable of conducting an auto land but needs the full instrument landing components to be completed safely. Recency for this type of approach is now generally conducted every 6 months in the simulator.

Jet engines from different manufacturers will have different spool up times from the idle position, the difference being whether they are 2 or 3 spool. This difference is only from the idle position. They normally get to the take off power setting around the same time.

Just trying to clear up some misconceptions from some of the above posts.

Hi,

Thoughts with all involved in this nasty accident. Looks like it hit the ground 500 metres early judging by the runway markings. Could be numerous reasons for the accident, but possibly a misjudged visual approach.

The instrument landing system has been off the air for that runway due to it being relocated so that may well be a contributory factor. Nothing to indicate that weather played a part with clear skies and light winds.

Things happen quickly on approach when your travelling at approx 250ft per second !

Anyone want to take a guess where this was taken?

Reports that all 172 passengers are safe.

Interesting runway. I don't remember it being that short.

Hi,

The runway there is in the region of 3000 metres long so it's plenty long enough for aircraft operations.

Glad all survived the ordeal.

I was asked this question at an interview and took a reasoned guess...

Did you pass the interview ?

I have a question for the AViation freaks out there

When landing with a 4 wheel bogey, which brake gets the hottest?

Generally the brakes on the downwind side will get slightly hotter. I guess it's partly due to brake cooling by convection as the upwind brakes are exposed to the wind. Next time I go flying I will have a more closer look to see how much difference it makes.

I am a current and qualified airline pilot. A blown tire is an a non-event, can happen on a perfect landing. AC tires endure enormous stresses, they don't last forever.

Hi,

I wouldn't go so far to say landing on a blown tire is a non event. You may experience direction control issues if landing with a flat main gear tire. The aircraft may yaw towards the flat tire or yaw away from the flat tire depending on the amount of brake application. Definitely something to consider if you have a tire pressure indication on the flight deck.

If they allow pheasants in business class I think I will be flying with another airline next time.

Hi,

No pheasants but falcons are allowed on board the aircraft in business or first class.

Hi,

Both runways operational but limited distance available on the easterly runway which in turn slows the movements down per hour. Operators advised to carry extra fuel for the ensuing delays.

I have flown in twice in the last few weeks, arriving at around 8am with around 10 minutes of extended vectoring to the north of the airfield. Not as bad as anticipated.

Some real issues with sink holes both on the runway and taxiways which can present issues when taxying a heavy aircraft.

Rgds.

I was on my way back from Nairobi to Amsterdam a few years ago. On a plane full of American church volunteers...not a fun flight. Anyway, across the isle was an extremely drunk guy. I think he was British, but not 100% sure. Spoke English. Kept bugging the girl next to me. And hassling anybody who would listen to him. They eventually cut him off and he was pissed. Yelling, cursing, really bad. The attendants tried to get him to calm down but he wouldn't.

Eventually the pilot came back and really laid into him. The big attendants moved the guy to the back of the plane and sat on each side of him.

As we landed, we were told not to get up as there was a medical emergency. Airport police came on, 3 huge dudes, and hauled the guy off in handcuffs. Everybody around us started clapping....

I wonder if he got into any trouble or was just put in the drunk tank?

Any pilot who ventures into the cabin to deal with a disruptive passenger is asking for trouble if they then get assaulted. Very foolish on their part.

Rstraining of a passenger really is a last resort, and the permission of the Captain is required in most airlines before the crew will carry it out. The definition used to determine whether the passenger is infact disruptive and whether to restrain is very clear.

Most aircraft have plug type doors fitted and flight locks that engage during the take off roll. The air pressure in the cabin during cruise flight is huge compared to outside, thus opening of the doors would be impossible.

What the crew want is for groundstaff to spot any potential disruptive passengers prior to boarding, thus avoiding any problem whilst airborne.

Rgds.

Hi Boogey,

whats a 77R ?.

Rgds.

have a 7 hour stopover in dubai on the way back from bkk,is there an affordable solution to get my head down for a few hours? any advice on the new terminal would be appreciated as well.

Hi,

there is an airport hotel, but by all accounts its expensive.

Perhaps you could pay to use a business lounge that would offer a recliner of sorts, otherwise the terminal has those style of seats but they are dificult to get.

Good luck.

Hi,

the entry doors are translating plug type doors. They actually move inwards and upwards when opening.

On the take off the aircraft starts to pressurise and at a certain speed the door flightlocks engage to prevent opening. Attached to each door handle is a vent panel to prevent unsafe pressurisation. On take off the door handle can still be moved slightly but the action of moving it only opens the vent panel slightly.

Once the pressure gets to about 2.5 PSI you would not be able to open the door, regardless of the flight locks being engaged.

Rgds.

Hi,

a sad day for Thai aviation. I have flown on Bangkok airways, and was very impressed by the level of service provided, including the safety aspect of the operation.

The airport operator can close an airport due to weather conditions. The Captain always has the ultimate responsibility for the safety of the passengers, crew and aircraft. If he/she deems it unsuitable to land in certain types of weather conditions then he/she will either hold until the conditions clear up, or divert to another suitable airport.

Landing in strong gusty conditions on a dry, slippery or contaminated runway can be quite challenging for sure. Its important to make a firm touchdown on a slippery/contaminated runway so the tyres punch though the layer of contamination on the runway to avoid aquaplaning. Directional control can be an issue, but the aircraft will have a reduced crosswind limit depending on whether the runway is dry slippery or contaminated. Some runways are grooved or porous which helps to disperse the water. Its very difficult to know the actual runway surface conditions. You would get an indication from Air Traffic Control of contamination depth and based on that you would then work out your landing performance.

If the fire engines are all damaged then the airport could potentially be closed for a while as there is no fire cover available for the operation of commercial flights.

My experience is that localised weather patterns normally pass through the airport within 30 minutes so the best policy is to stay on the ground or hold if airborne and fuel is sufficient.

Rgds

i actually work on the 380 , building it , not flying it

Why did you make it so ugly then hehe !!.

If you want to talk about ugly airplanes, then you can't beat that old dinosaur, the 747, for being ugly!

Hi there,

have to disagree, the B747 looks good and thats confirmed by, "if it looks right it will fly right". The A380 is an impressive looking machine, but it is ugly !.

Rgds.

i actually work on the 380 , building it , not flying it

Why did you make it so ugly then hehe !!.

Hi,

regarding the tech prob, glad to see initiative being used to get the aircraft back to base, perfectly safe and sensible decision by all concerned.

I would imagine all airlines will have an Safety And Emergencies Procedure (SEP) course in place. What is actually involved in the course will however vary quite dramatically i am sure, depending on where the airline comes from. The crew will have attended a first aid course, and the senior cabin crew members will be trained on the use of the defibrillator carried on board.

Everybody will react differently to a potentially stressfull situation on board and aircraft. Its not something you could really determine 100% from a recruitment/selection procedure.

It would be silly for a pilot to go into the cabin and get involved. That job is delegated to the cabin crew and the pilots job is to fly the aircaft !.

Some aicraft have onboard sat communication with direct dial to a medlink facility manned 24 hrs per day. If a passenger falls sick onboard the crew can contact medlink, explain the symtoms, and then make a decision based on the advice they offer. Most of the time it can be dealt with onboard, occasionally it can end up with a diversion.

New generation aircraft are very straight forward to operate, thus no requirement for a flight engineer. The engineers panel has been incorporated into the overhead panel on the flightdeck and generally does not require much interaction during a normal flight.

A Boeing 777-300 in a 2 class config will hold well over 400 passengers.

Rgds.