Boeing only mentions prior 80 (79.9) and after 80 (80.1). Exactly 80 knots is a grey area :E

Mach .72 Rotate Captain!:D

Tricycle speed record
 

Having trouble following the travel of the thread about the a/c that reached orbital speed on take-off. Does anyone know where the kids have put it now?

Last I heard it was due to catch up with Voyager 1 anytime within the next 24 hours. Watch this space! ;)

http://planete.gaia.free.fr/images/i...er.pioneer.JPG

I recall from many years ago, my company asked its crews ti time how long it took to get to 100 knots (nil wind) in a 737-200 at varying weights at ISA +10 sea level. About 50 take off's were measured. In all cases it was between 40-45 seconds and it turned out as quite a useful acceleration check. 30 seconds to reach 150 knots would require an afterburner and 737's don't come equipped with one of those.

I Am going for thar idea that the speed was reported in KPH not MPH. I could be wrong, but I think the tyres would be disintegrating at 300 mph.

737 excessive rotation speed - a hard act to follow
 

Notwithstanding the tires disintegration issue I simply don't think that the 737 has anywhere near the necessary thrust to achieve 300 mph after 10000ft...

Are there any western airline pilots on this board who upon hearing " 80 kts " from the FO and looking at their ASI and seeing a number much smaller; would continue the tskeoff rather than immediately calling for the reject ?

How do you know which one is accurate?

Open the window:p

Above 80 knots (which would be the case), I'm only stopping for fire, engine failure etc, so I'd be happy to continue. A check of the standby ASI to see whose instrument is reading correctly and then use that to take to the air. Once airborne a more detailed check to establish the problem (almost certainly an ADC fault), while flying pitch and power if there's any doubt as to whose ASI is correct. Of course, with RVSM considerations v ADC etc I'll almost certainly not be going anywhere but I don't believe it is a reason for a 'high speed' rejected take-off.

An 80 kt reject on a 10,000 foot runway is not a big deal. I don't understand why you would want to take an obviously broken airplane flying......

The manual
 

I've had this happen to me, I had an "IAS disagree" message show up on my PFD right after I made the "80 knots" call out. I was flying a brand new 737 NG, by brand new I mean an NG with probably 3 or 4 months of continuous airline use.


Our manual says that past 80 knots we only reject a take off for Engine failure, fire, unsafe/unable to fly. And as the previous pilot mentioned you fly specific pitch and power settings, and continuously monitor your standby instrument.


Eventually the message disappeared, only to come back during approach phase. Upon touchdown both EEC's went to alternate mode. The plane was written up, we told maintenance and we where given another plane for the flight to another city. End of story.

Not saying it would be a big deal, Big Pistons, but (a)SOPs are there for a reason (b)take-off is not the time to be deciding if you or the manufacturer know better (c)an 'obviously broken' ASI is not a big deal to be taking into the air....especially when you can almost guarantee it's going to be a button push to solve the snag. Remember, we're not talking about a single-source pitot-static instrument here but a multi-source air data computer. The ASI problem is solved by selecting a different ADC, simple as that.

"Our manual says that past 80 knots we only reject a take off for Engine failure, fire, unsafe/unable to fly. And as the previous pilot mentioned you fly specific pitch and power settings, and continuously monitor your standby instrument".

I think that you will find that most pilots would feel that erroneous ASI is considered as"unsafe" to fly. You would be an idiot to take an aeroplane into the sky with said problem. At 80(or 100 in an Airbus), the ability to stop is really not a problem and is by far the better option IMHO.

ASI problems are a big deal even if the drill is simple. Why take a problem up into the air only to return and land overweight or have to burn fuel tonnes of fuel? I would reject even at 110. Rejecting at that speed is a less bigger deal. Granted very soon after that it becomes a totally different ball game.

Are there not three airspeed indicators on most jets?

Why risk a high speed RTO for a minor snag? There is plenty enough redundancy to safely fly with one ASI failed.

I recently had an ASI failure during the take off roll. I compared the other four ASIs and we continued. Once clean I turned around and reset the ASI CB which sorted out the problem. I'd have looked pretty stupid having either rejected at high speed or landed overweight wouldn't I?

Oldaircrew, I don't know your back ground but I think you'll find that most pilots would NOT reject for a single ASI failure as it isn't unsafe. I think you'll find most pilots will follow SOPs and the brief.

80 kts is hardly high speed and not far in excess of what you could take a high speed exit at after landing. Given a 3000m runway I'd be stopping and probably would't even need the brake fans afterwards. Why continue accelerating when there is a problem and safe stop is not in doubt ?

Obviously closer to V1 you'd be GO minded and would need a very good reason to reject, even a hydraulic system failure wouldn't be enough reason to stop.

Just for info, Airbus use 100 kts.

Chesty,

I would beg to differ. At that point an RTO is a minor affair. To try and determine which ASI is incorrect at that point in the T/O is a bad idea. It may not be as cut and dried as a simple failure of one ASI. You could merely have a difference of opinion of 10-15kts. I don't remember the Boeing but the airbus(330/340) has a limit of + or -6kts on the ground.

I would personally rather stop and look a little silly than go, cock the identification of the problem up and look dead.

I'd like to think you wouldn't die because of one erroneous ASI.

Metro Man, how do you know you're only doing 80kts? What if you're actually doing 100? What does your brief say?

That is why it is prudent to check the ground speed during the take off if you have a suspicion that one of the ASI's is giving erroneous information. The Boeing FCTM mentions that. If all else fails, then rather than doing a high speed reject it is better for everyone concerned to continue the take off and rotate on the ground speed indication with wind adjustment of course. Then sort out the problem at your leisure in the air. This is where simulator practice comes into play.

Centaurus,

Once again I beg to differ. Whilst I agree that it is good airmanship to cross check GS and Airspeed, not everyone does it. Time is an issue here.

As both ASIs are dead until 30 kts in the bus, you have about 15 secs to determine if you have an issue with the ASI at the same time doing the T/O calls and engine instrument monitoring. 100 kts comes up in about 20-25 seconds from the application of Flex(once again I am using the bus as I do not remember Boeing at all).

I think it is a mistake to continue the T/O and take an unsafe aircraft into the air. I know that we have procedures to deal with unreliable airspeed but the need to identify the problem correctly makes it less risky to stop rather than go as far as I am concerned.

People, you forget that in real life, it will take you many seconds to realize that something is wrong. Just a few seconds brain processing, and you have 120+ knots. And if both captain and co-pilot airspeed indicators (unlikely) have failed, you have no idea of the actual speed. That could easily be the recipe for an overrun on a short runway (see AirBerlin in Dortmund).

Unreliable airspeed should be a minor problem for a proficient pilot. Definitely not "unsafe to fly" in my opinion. And apparently not in the opinion of Boeing either (no mention to reject for unreliable airspeed above 80).

Boys, another chance to blow and pontificate! The Indonesians are suckers for punishment.

Have you read this thread? http://www.pprune.org/rumours-news/5...s-air-phl.html

BRE was right about it : [QUOTE]BRE

Join Date: Mar 2007
Location: Europe
Posts: 114
If this had been a Korean or French airline, the bashing would have covered 10 pages by now...
[QUOTE]

Only a just 4 of days and it has gone to four pages for this thread!

If the ASIs read differently then one of them will read 80 before the other, at this stage the speed call or lack of should indicate a discrepancy. When I'm PF I still check cockpit indications as I'm the one who makes the decision to reject.

Airbus use the
STOP STOP STOP GO GO GO

model to deal with failures as speed increases.

What a marvelous idea. You can have the PNF making call-outs with ever increasing rising inflection of his voice during the take off run of STOP stop stop - Get ready to go - go Go Go ROTATE:ok::ok:

Unless one of them stops working after 80...

Obviously the model is a bit too difficult for some people, it simply means at low speed you should be more inclined to stop in the event of a problem and at higher speed you should be more inclined to continue..

For info, Airbus inhibit most warnings during the take off roll and only something serious such as a fire will appear.

What if all the ASIs stop working, the attitude instruments all disagree, the altimeters freeze up and you go IMC at 50ft, your diversion airfields all go below minimum, the other pilot has a heart attack and the radios fail.Then you would probably wish you had stopped while you were able to.

Let's all stay in bed. Life is too dangerous! :}

Chesty, your example has the benefit of hindsight. If on the other hand you departed with a heavy plane and it was a blocked tube that you diagnosed, somehow I highly doubt you'd be happy to fly through the ITCZ on your way to South America. You'd be looking to land ASAP and not before dumping $100,000 worth of fuel and probably feeling silly due to that. I think there is an unjustified amount of attention being paid to go-mindedness. Don't get me wrong, I'm all for it and totally agree with the concept but considering the maths and theory clears you all the way up to V1, 10-20kts is sufficient for go-mindedness.

On top of all, consider that on an Airbus, the first time you make the ASI crosscheck is really the first you get to realise if there's a disagreement. What are we saying then that we would NEVER reject due to speed problems because by 100-110Kts its too late??? If we cannot stop from those kinds of speeds safely on 10,000ft of asphalt even when wet, something is wrong with our training, the aircraft or even the regulations which allow for performance criteria and runway design that cannot support RTOs from such speeds.

That is why Boeing has a policy of the airspeed check at 80 knots rather than the 100 knots of Airbus. Better pick the problem early than later further down the runway.

A wise pilot will cross-check his ground speed reading with his ASI reading at 80 knots. This is nicely covered in the FCTM with the following: "A pitot system blocked by protective covers or foreign objects can result in no airspeed indication, or airspeed indications that vary between instruments. It is important that aircrews ensure airspeed indicators are functioning and reasonable at the 80 knot call-out. If the accuracy of either primary airspeed indication is in question, reference the standby airspeed indicator. Another source of information is the ground speed indication. Early recognition of a malfunction is important in making a sound go/stop decision.

It is most important and good airmanship that if the PM does not make the required call-out (eg 80 knots, V1 and VR) the PF should make it.

An example (happened in Australia) of where this could have prevented a high speed abort involved an A330 on take off. An insect blocked the captain's ASI tube resulting in a significantly under-reading ASI. The PF was the first officer. As the A330 passed 100 knots the PF received no call from the captain. He did not query this omission and continued the take off roll. Approaching V1 the captain called "100 knots" The first officer as PF realised only then at the late stage of the take off that something was drastically wrong.

The first officer queried the captain on his 100 knot call when the F/O ASI was showing close to V1. The captain decided to abort the take off and taking control performed a high speed reject. On returning to the tarmac to rectify the defect the tyres deflated due to excessive heating caused by the abort.

A simple "110 knots my side" by the first officer as PF would have alerted the captain to a problem with his own ASI. Better still, a comparison of ground speed versus IAS at an appropriate time early in the take off roll would also alerted the captain to the impending problem and prevented a late high speed abort with it's concomitant hazards.

Whether it is an 80 knot or 100 knot call depending on manufacturer philosophy, for many pilots it becomes a parrot like Ho Hum call. On many occasions the call is made late. Call it what you like but it boils down to complacency and poor airmanship.

Why would you need to land ASAP? Why couldn't you continue to destination?

FWIW, (777) I'd stop, there is no time to conclusively decide on the cause, it it therefore IMHO inherently unsafe and moreover unwise to continue....

Where is this report anyway....Bulldust I think..

On Airbus, at '100 knots' call you say 'checked', and if not correct and error a 'unsafe' margin you reject....simple.

The 100kt Speed selected by Airbus would have the same 'pilot recognition' time delay as other speeds on takeoff.

Why would you accept a primary ASI error then take-off :ugh:
Rotating or stopping of the wrong one at V1/Vr could be far worse then 100kts with some error.

The speed error between 100kts and normal weight V1's would be sufficient to stop in 95% cases. Other short RWY's=GO minded anyway...

FFRATS

737 excessive rotation speed - a hard act to follow
 

Was there ever a report on this one?!