Re: Dash-8 incorrect takeoff configuration.

From	Daryl <dwalford@westpine.com.au>
Newsgroups	aus.aviation
Subject	Re: Dash-8 incorrect takeoff configuration.
Date	2025-01-25 22:36 +1100
Message-ID	<lvk0m9Fk87oU1@mid.individual.net> (permalink)
References	(4 earlier) <lvgpdlF3t5nU2@mid.individual.net> <op.20vdh9dzbyq249@pvr2.lan> <lvhkmqF8lmsU1@mid.individual.net> <lvihukFd5foU1@mid.individual.net> <lvjmkaFiof3U1@mid.individual.net>

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On 25/1/2025 7:44 pm, Sylvia Else wrote:
> On 25-Jan-25 6:19 am, Daryl wrote:
>> On 25/1/2025 12:59 am, Sylvia Else wrote:
>>> On 24-Jan-25 4:21 pm, Rod Speed wrote:
>>>> Sylvia Else <sylvia@email.invalid> wrote
>>>>> Rod Speed wrote
>>>>>> Sylvia Else <sylvia@email.invalid> wrote
>>>>>>> Rod Speed wrote
>>>>>>>> Sylvia Else <sylvia@email.invalid> wrote
>>>>
>>>>>>>>> https://www.atsb.gov.au/publications/ 
>>>>>>>>> investigation_reports/2025/ report/ao-2024-038
>>>>
>>>>>>>>> It's time all public transport aircraft had takeoff
>>>>>>>>> performance  monitoring, no matter the size.
>>>>
>>>>>>>> That isnt going to result in the problem  being
>>>>>>>> fixed quickly enough  to  stop an accident
>>>>
>>>>>>> Well before an abort becomes risky, the system has enough 
>>>>>>> informationto  determine whether the crew calculated v1 and vr 
>>>>>>> are correct,
>>>>
>>>>>> Bullshit with that incorrect flaps setting.
>>>>
>>>>>>> and whether  the aircraft will be able  toboth continue a 
>>>>>>> takeoff, and stop, at v1.
>>>>
>>>>>> Bullshit with that incorrect flaps setting, let alone
>>>>>> tell the pilots that the flaps setting is wrong.
>>>>
>>>>>>  It would make much more sense to compare the
>>>>>> actual settings with that has been entered at the
>>>>>> preflight config calculations and tell the pilots
>>>>>> that they have not set what was required with
>>>>>> flaps and boost etc before they actually applied
>>>>>> takeoff power and not allow takeoff power to be
>>>>>> applied before those were set correctly.
>>>>
>>>>>>> It can issue an abort alert if not.
>>>>
>>>>>>  See above
>>>>
>>>>>>> This covers at least miscalculated v1, miscalculated vr, wrong 
>>>>>>> thrust settings, wrong flap settings, starting from the wrong 
>>>>>>> intersection, takeoff from the wrong runway, and no doubt others 
>>>>>>> that I haven't even thought of.
>>>>
>>>>>> It would be stupid to try to measure that while taking off
>>>>>> instead of doing that before takeoff power is applied
>>>>
>>>>>> Yes, there is also a different problem with the engines
>>>>>> not being able to deliver the power they were assumed
>>>>>> to be able to deliver the power they were supposed to
>>>>>> be able to deliver in the preflight calculations, but that
>>>>>> was not the case in the incident being discussed and
>>>>>> it would be much easier to discover than much earlier
>>>>>> in the takeoff run than V1 or VR
>>>>
>>>>> The question the system needs to ask is "In the current 
>>>>> configuration, with the measured acceleration [*], current 
>>>>> airspeed, and current position on the current runway, can the 
>>>>> aircraft reach the specified V1 at a point where it can continue 
>>>>> the takeoff or abort, and will it be able to rotate at the 
>>>>> specified Vr.
>>>>
>>>> The problem with that approach is that is far too late
>>>> during the takeoff run to be doing that by measurement
>>>> when its much too late for the pilots to be fixing what
>>>> the problem is, particularly when the engines arent
>>>> actually performing the way they were meant to when
>>>> the prefight calculations were done
>>>
>>> There would be no expectation that the pilots would fix it. The idea 
>>> is to abort the takeoff while that can still be done safely.
>>
>> I assume that you are talking about some sort of automated system to 
>> alert pilots of a configuration error?
>> If so wouldn't that rely on data input by the pilots prior to takeoff 
>> so the system would be only as good as the data therefore it doesn't 
>> completely eliminate the chances of an error?
>> In this incident did the pilots self report?
>> If they didn't why would the ATSB investigate?
>>
>>
>>
>>
> 
> My thinking is that the system has access to the settings for flap, 
> thrust, mass, V1 and Vr. None of these is assumed to be correct.
> 
> Also access to GPS and airspeed.
> 
> In the following, the system would allow some level of discrepancy so as 
> not to cause unnecessary aborts.
> 
> Once the aircraft is accelerating, its direction together with the GPS 
> calculated position allows the system to determine which runway the 
> aircraft is on (position alone may not be sufficient, where runways 
> intersect).
> 
> The acceleration to be expected from a given thrust setting depends on 
> the aircraft's mass, and its airspeed. So the system waits until there 
> is a reliable airspeed. It then can calculate the mass from the expected 
> thrust, the acceleration and the airspeed. The result should match the 
> setting. If it doesn't this means that either the mass is set wrong, or 
> the expected thrust, based on the thrust setting, is not being achieved. 
> Either of these aborts the takeoff.
> 
> Vr can now be calculated based the mass and flap setting. If the 
> calculated Vr differs from the set Vr, this aborts the takeoff.
> 
>  From the current position, the acceleration and the mass, the braking 
> distance can be calculated [*], and from that V1. If the calculated V1 
> is lower than the set V1, then abort take off.
> 
> [*] This is one area of uncertainty, since braking distance depends on 
> runway condition (wet, dry, etc.).
> 
> Sylvia.
> 
> 
My piloting experience is 5hrs training in a helicopter so not much but 
to me it sounds a bit complex and still open to input error to be of 
much value?
Might be feasible on newer complex aircraft but retrofitting such a 
system on older aircraft would most likely be very expensive and maybe 
not even possible.
You didn't answer the question about self reporting, was that mentioned 
in the ATSB report?


-- 
Daryl

Thread

Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-21 13:28 +0800
  Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-23 04:21 +1100
    Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-23 12:50 +0800
      Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-23 20:09 +1100
        Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-24 14:14 +0800
          Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-24 19:21 +1100
            Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-24 21:59 +0800
              Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-25 03:46 +1100
              Re: Dash-8 incorrect takeoff configuration. Daryl <dwalford@westpine.com.au> - 2025-01-25 09:19 +1100
                Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-25 13:17 +0800
                Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-25 19:34 +1100
                Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-25 16:44 +0800
                Re: Dash-8 incorrect takeoff configuration. Daryl <dwalford@westpine.com.au> - 2025-01-25 22:36 +1100
                Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-25 22:12 +0800
                Re: Dash-8 incorrect takeoff configuration. Daryl <dwalford@westpine.com.au> - 2025-01-26 09:36 +1100
                Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-26 10:07 +1100
                Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-26 02:21 +1100
                Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-26 16:29 +0800
                Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-26 20:14 +1100
                Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-27 12:17 +0800
                Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-27 19:52 +1100
                Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-27 16:56 +0800
                Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-28 04:33 +1100
                Re: Dash-8 incorrect takeoff configuration. Sylvia Else <sylvia@email.invalid> - 2025-01-28 11:52 +0800
                Re: Dash-8 incorrect takeoff configuration. "Rod Speed" <rod.speed.aaa@gmail.com> - 2025-01-28 15:57 +1100

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