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ghutcheon

Correct procedure for aborting takeoff

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Prior to take off I have FMC set up, arm AutoBrake, AutoThrottle, advance throttles to 70% N1 and press TOGA button to engage TOGA. All is good.Sometime before V1 I elect to abort T/off. What is the correct procedure to follow? If I move my throttles back to idle there is no effect and hitting the brakes also does not stop the engines running at the assigned take off power? I use the CH products yoke and rudder set with included throttle axis on the yoke. Does one need to disarm the autothrottle and then pull back on the levers? What triggers the autobrakes to activate? Also, I think the spoilers should deploy during such an event?Any advice or help with the correct procedure for aborting t/off will be greatly appreciated.GregH

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Ahhhh,When in doubt read the manual.... :-)Thanks Niels.

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OK, I read the manual. I checked the box for Controls Override for the throttle. Can anyone confirm that the spoilers will only deploy during a rejected takeoff if the Auto Brake is set to RTO? My spoilers don't deploy at any speed when the reject is initiated with Autobrake disarmed during a very quick test.

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Close the thrust levers, apply maximum symmetrical reverse (if above 80kts), manually deploy the speedbrakes/spoilers, monitor RTO autobrake functions, apply full manual braking as and when required. Call 80, 60, 40, come to a complete stop on the runway, assess the situation, call ATC and go through the QRH.............;).Remember reverse and spoilers are most effective at initial deployment/high speed- after that they become FOD catchers and bored (intentional spelling for the boards) :).Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png

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Hi Carl,Thank you for this info. I guess there would be no merit in deploying reverse thrust and spoilers if a take off was rejected before reaching 80 knots?One more pressing question on all this though. Reading thru the PMDG manuals (Type Rating Course) it says and I quote " Initiating the reject will cause the spoilers to deploy and the autobrake will engage to bring the airplane to a complete stop"When I initiate the abort by moving the throttles back to idle, the autobrake kicks in but spoilers do not deploy unless I reverse thrust. This happens even if the abort it done well over 80 knots, close to V1. Is this correct or am I doing something wrong causing the spoilers to fail to deploy automatically? My throttle does not have reverse thrust detent, so I have to hit F2 key. Only when I do this, do the spoilers deploy. Also, does reverse thrust alway activate spoilers or only on an abort?GregH

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Guest ColdBear

Greg,Just to add a note to carls respons witch is all correct. There are two scenarios to consider:1) Low speed RTO, GS below 80kts witch is where you would stop for all malfunktions. Doing this part you must disconnect the A/T because it's still in THR REF.2) High speed RTO, GS above 80kts. This is the more serius one and normally you would only stop for an engine failure, fire or a master warning. Doing this stage you shall just retard the thrust lever and bring it into revers(max or idle depending on runway lenght and RTO speed). monitor the autobrakes and steer the aeroplane. Call ATC tell them what your doing and if nessecery(sp?) evacuate on the runway.Hope this helps :-sun1Martin

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Pulling the throttles to idle will only activate the autobrakes (RTO). The type rating course has probably glossed over the fine details.Unless someone has changed the rules, I understood that the correct procedure was to apply the speedbrakes manually before using reverse thrust. The speebrakes will auto-deploy if you pull up on the reverse thrust levers, but either aviation regulations or airline procedures would have you pull the speedbrake lever first (manually). As some manuals state, stopping distances are not predicated (based) on the use of reverse thrust. That is, reversers are a luxury, so to speak.Note that the autospeedbrake will drive the speedbrake lever back when you do manually pull the speedbrake lever out of the DN detent (prior to pulling on the reversers).Hope the real pilots will chime in here... ;)Cheers.Q> イアン

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As Q so subtly states- I am not type rated in the 746 (although I would like to think that my SEL rating makes me a real pilot ;))- and he is correct to state that manual deployment of the speedbrake ought to come before deploying symetrical reverse. Is easier (quicker) for me to go into reverse and then check for spoiler deployment, but as in all things, I want to keep it "as real as possible" so I shall re-structure my flow.Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png

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I am experiencing the same problem as described by the original poster in this thread;"Sometime before V1 I elect to abort T/off. What is the correct procedure to follow? If I move my throttles back to idle there is no effect and hitting the brakes also does not stop the engines running at the assigned take off power? I use the CH products yoke and rudder set with included throttle axis on the yoke. Does one need to disarm the autothrottle and then pull back on the levers? What triggers the autobrakes to activate?"Due to the rather cryptic nature of the initial response to this post - "read the manual" - it is not clear to me exactly what might have been the original poster's problem and whether that is in fact my problem. It would appear, however, that the original poster had failed to check the throttle box of the Controls Override section in the AFDS section of the settings. I have this box checked, yet I still get no throttle retardation when pulling the throttle back to idle and no autobraking. The plane just continues to accelerate and take off. What am I doing wrong? I am experiencing this problem with both the CH Products yoke and pedals and the Saitek yoke and pedals. I am running FSX Acceleration with Windows XP SP3. And I have installed the v2.10 upgrade for the 747.Also, it is not clear to me how one uses the alternative method described in the referenced type course 2. it says to setup a key command for the MCP Abort TO/Discon AT command. However, in FSX there is no such command. Exactly what command, if any, is the FSX counterpart?Thanks, Robert

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From Coldbear's reply above - "1) Low speed RTO, GS below 80kts witch is where you would stop for all malfunktions. Doing this part you must disconnect the A/T because it's still in THR REF.2) High speed RTO, GS above 80kts. This is the more serius one and normally you would only stop for an engine failure, fire or a master warning. Doing this stage you shall just retard the thrust lever and bring it into revers(max or idle depending on runway lenght and RTO speed). monitor the autobrakes and steer the aeroplane. Call ATC tell them what your doing and if nessecery(sp?) evacuate on the runway."

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Unfortunately, the High speed TRO doesn't work for me. The plane keeps accelerating and takes off.Robert

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"What triggers the autobrakes to activate?"The throttles must be brought back to idle when the average wheelspeed* is above 85kts. The real world, the airplane cross-checks this sensed wheelspeed with the IRU groundspeed for validity. There must be no faults with the Autobrake system and your feet must not be pushing on the pedals.*average wheelspeed is defined as the average of the (8) "forward" main gear wheels, with the two highest and two lowest wheelspeeds discarded (just in case you thought it wasn't complicated enough) :)Note that, unlike normal landing autobrakes, if you do push on the pedals, the Autobrake switch will not trip to disarm, but the autobrakes will deactivate... until all the prerequisites for RTO are once again satisfied.At 65kts, the 744 A/T goes into HOLD mode, so it's not really necessary to disarm the A/T (at least in the real world).Cheers.Q> イアン

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I'm confused by this response. I'm not applying the brakes. Rather, I'm waiting for the autobrakes to kick in. And they don't - and in the meantime the plane keeps accelerating even though I've reduced the throttles to idle.Robert

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What you are doing is correct. I just added this stuff for general interest.Somehow your settings are not being recognised by the sim. If your thrust is not retarding when you are pulling back on your joystick throttle during high speed aborts, then the autobrakes won't work.Sorry, I don't have FSX, so I don't think I can offer much help here.Rgds.Q>

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Thanks for the clarification. So I guess the question now is why don't the throttles to to idle when I pull them back?Robert

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Guest hangar744

Hi guys,Qavion mentioned something really important. Anybody noticed it?***That is, reversers are a luxury, so to speak.***In other words...RTO executed on dry (non-contaminated) runway, zero slope, 16 (carbon no-fade) brakes servicable, with normal antiskid servicable...reverse thrust has NO effect whatsoever on accelerate-stop distance.regards,delcom

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Actually, I hope I didn't give that impression.The stopping distance tables are based on thrust reversers not being available. However, if the reversers are available, they DO help the aircraft to stop.RTO braking has no set deceleration limit (unlike the landing settings 1~Max Auto). If you can stop the aircraft in a shorter time/distance with the aid of reverse thrust, then the brakes will be used for a shorter time (so, in theory, less heat will be generated in the brakes). In fact, some AOM's say that if you are not sure you are going to have enough runway to stop, you should continue to use the reversers even below the recommended stowing speed: Damaging the engines is less important than the aircraft running off the end of the runway.Cheers.Q> Ян

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im a little confused hereif you think you dont have enough runway to stop and you are near V1 wouldint it be safer to just takeoff anyway and take the problems in the air rather than comming to a grinding engine reversing speedbrake stop???besides i always thought V1 was the last point ( no matter how long the runway is ) that the brakes can safely stop the plane.after all, thats what happend to this plane:http://www.jetphotos.net/news/index.php?bl...1&c=1&tb=1&pb=1

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Actually, I was considering the cases where you have correctly aborted the takeoff prior to the tabulated/computed V1 speed, but due to, say a failure or some unforseen circumstance, you find the end of the runway closer than you had anticipated ;)Also applies to landings.

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Guest hangar744

sorry guys,my previous post contained totally insane information about RTO.***In other words...RTO executed on dry (non-contaminated) runway, zero slope, 16 (carbon no-fade) brakes servicable, with normal antiskid servicable...reverse thrust has NO effect whatsoever on accelerate-stop distance.***Please ignore this, I was gonna write something else. It's just turned out non-sense.regards,delcom

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a high speed RTO is a very complicated manuver to accomplish. ill give an example here: youre weight is over 700000LBS and youre V1 speed is around 165KTS.if your barreling down the runway and you get a problem at 140KTS ( and youre already half way down the runway ), that plane is not going to stop in time. even with a non contaminated runway with 0 slope or an uphill slope. it would be safer for you and the plane if you took whatever problem you had into the air.i would rather take my chances at around 140KTS with full flaps out at the runway touchdown zone, than being at 150KTS halfway down the runway.on another note im willing to bet 10:1 odds that the noise the flight crew heard on the aborted takeoff was the freight not being properly secured.

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Kevin:With all respect, if you did hear cargo moving- an RTO makes incredible sense- after all, who knows where your C of G would end up- probably somewhere you could not fly! I'm glad the Kalitta crew survived- good job!Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP3 | 2 x APC UPS | Coolermaster Stacker 830 SE | Gigabyte P35 DS3R | e8500 @ 4gHz | Tuniq Tower 120 | EVGA 8800GT 512MB | Creative X-Fi Fatal1ty | 2 x 1 GB Corsair XMS2 | 2 x 320GB WD Caviar RAID 0 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |

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i wasint referring to them i was referring to RTO's in general. they did make the right desision hense thats why i think it was the cargo.

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