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Friday I was on a plane from MXP to Prague, should have been a 737-400, and the take off was preceded by something I'm not sure what it was: probably a pre-flight checklist, but it's the first time I see something like this:

  • The plane got pushed back by a tractor from ramps to apron - at least, I think it was the apron- and turned (still by the tractor) in the right direction for the taxiway
  • Engines thrust was increased and decreased a few times, keeping them at "high" levels for a bit
  • Control surfaces were checked as usual

I'm used to pilots checking control's surfaces either while still at ramps or on the taxiway while waiting for their turn to take off, or just at the beginning of the runway, but never seen anything different and never seen "testing" the engines that way, and it got me wondered about check list frequencies.

Was that routine some kind of checklist? And if so, is there a specific regulation about how often it must be performed? (and, by the way...I know that it's possibile to load fuel even with passenger on board, but...testing engines with plane full loaded? Isn't it a bit too dangerous?)

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  • $\begingroup$ And to not litter the answer: if the pilot of that flight is by chance reading this...BEST-LANDING-EVER. Seriously amazing. The only description I can come off is "went from flying in the air to flying on the ground". Never ever seen that level of precision and control of the aircraft, absolutely spectacular! $\endgroup$ – motoDrizzt Sep 5 '16 at 15:44
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    $\begingroup$ Maybe some maintenance had been done and the pilot wanted to check that it had cured the symptoms of a previously reported problem? $\endgroup$ – RedGrittyBrick Sep 5 '16 at 16:14
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    $\begingroup$ Can be many things: 1- An engine check for any maintenance request. <BR>2- depending on the ground softness sometimes pilots have to increase the power to get a heavy aircraft to move <BR>3- improbably a run up check for icing but I think on Friday was still good weather in Italy. <BR>need more details, like was the aircraft static? Did the pushback truck disconnected ? This kind of test does nothing to do with checklists, normal nor emergency checklist. <BR>Sorry if I could not give you a streight answer. $\endgroup$ – Manolo Sep 5 '16 at 23:22
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    $\begingroup$ @motoDrizzt In regards to your BEST-LANDING-EVER comment, remember that luck as well as skill enter in to the quality of a landing. When you do something thousands of times, even a poor pilot sometimes gets an exceptional landing and an exceptional pilot a poor landing. The condition of the runway surface as well as the aircraft type also play a significant roll. $\endgroup$ – Terry Sep 6 '16 at 16:08
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    $\begingroup$ @Terry I know, obviously, it's always a bit of this and a bit of that: luck, skills, weather...e.g. it's not pilot's fault if he has to land in a strong side wind nor he's a better pilot if he land in ideal conditions. So, as I know all of this and I never complain about a rough landing, I feel there is nothing wrong in being impressed by a good landing. It was, anyway, the best I ever experienced and being positive costs nothing :-) $\endgroup$ – motoDrizzt Sep 6 '16 at 17:39
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For an airline crew, the Before Takeoff Checklist is performed once before every takeoff. There is normally no "run up" associated with such a checklist for jet aircraft.

Depending on what else is going on, there are reasons that engine power might be advanced then reduced, and it would be speculation as to what the reason for that was on your particular flight.

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The amount of times they do the checklist is not important. There's things that are repeated between checklists. For example, some aircraft have control surface checks both on the ramp and while taxiing. Regarding the engine run-up, the pilot would not do it if it was hazardous to passengers. Engine run-ups are usually performed somewhere between the ramp and takeoff. Engine run-ups are a must. Other reasons for engine run-ups could be carb cleansing (for non-fuel injection pistons), engine temperature adjustments, etc.

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    $\begingroup$ I'd love to accept the answer, but as it is it lacks a bit of details. As it stand, for example, it sounds like the pre-flight check list is not mandatory ("The amount of times they do the checklist is not important"), and "engine run-up" means...? $\endgroup$ – motoDrizzt Sep 11 '16 at 11:55
  • $\begingroup$ I would be very surprised to know that preflight checklist is not mandatory. please google engine run-up. $\endgroup$ – user6035379 Sep 13 '16 at 10:47
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    $\begingroup$ "The amount of times they do the checklist is not important." Disagree. At least once is surely required. $\endgroup$ – David Richerby Nov 6 '16 at 13:13
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Engines thrust was increased and decreased a few times, keeping them at "high" levels for a bit

This could be as a result of a recent maintenance note on the aircraft, which resulted in some configuration changes or modifications to the engines, thrusts, throttles or any number of things in the middle.

If my memory is correct, the 737-400 is not a fly-by-wire aircraft; so there is a lot of mechanical stuff going on.

So it could be simple run up to verify things in the mechanics log.

I'm used to pilots checking control's surfaces either while still at ramps or on the taxiway while waiting for their turn to take off, or just at the beginning of the runway, but never seen anything different and never seen "testing" the engines that way, and it got me wondered about check list frequencies.

Unless some extraordinary exception is in place, control surfaces are not checked at the gate or at the ramp; simply because most of these test have to be performed post engine startup in order to ensure all systems and redundancies are tested.

If flight controls are being tested (ie, full range being tested) on the runway this is definitely not normal.

(and, by the way...I know that it's possibile to load fuel even with passenger on board, but...testing engines with plane full loaded? Isn't it a bit too dangerous?)

Most commercial airplanes can be fueled with the engines running (but at idle), but for safety reasons, it is almost never done.

Having passengers on board during refueling happens quite often. You'll know its going on because the crew will inform passengers to be seated.

Regarding your main question about checklists - they must be performed once at the respected stage of flight. So a taxi checklist is done before each taxi, takeoff before each takeoff and so on.

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  • $\begingroup$ I don't quite understand your response to the third quoted section of the question. The asker clearly states that they know it's OK to fuel with passengers on board but the question is about testing engines with passengers on board. Your response just reiterates that it's OK to fuel with passengers on board and says nothing about testing engines, which is the only thing being asked about. $\endgroup$ – David Richerby Nov 6 '16 at 13:12

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