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.