Re: Dash-8 incorrect takeoff configuration.

From	Daryl <dwalford@westpine.com.au>
Newsgroups	aus.aviation
Subject	Re: Dash-8 incorrect takeoff configuration.
Date	2025-01-26 09:36 +1100
Message-ID	<lvl7bkFq9oqU1@mid.individual.net> (permalink)
References	(6 earlier) <lvhkmqF8lmsU1@mid.individual.net> <lvihukFd5foU1@mid.individual.net> <lvjmkaFiof3U1@mid.individual.net> <lvk0m9Fk87oU1@mid.individual.net> <lvk9r1FllumU1@mid.individual.net>

Show all headers | View raw

On 26/1/2025 1:12 am, Sylvia Else wrote:
> On 25-Jan-25 7:36 pm, Daryl wrote:
>> 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?
>>
>>
> 
> I can't find a specific reference to how this came to the attention of 
> the ATSB. Most likely it was reported to Qantas Link by the pilots, and 
> Qantas Link then reported it to the ATSB.
> 
> Sylvia.


Would it be mandatory for the pilots to report to the airline or just 
good practice?
If the airlines culture encouraged them to report without consequence 
then its a good safety measure, maybe that's why airlines in Australia 
have such a good safety record?

-- 
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

csiph-web