Elche said
VMC Minimum Control Speed
VMCA Minimum Control Airspeed Airborne (Red line speed)
From CAAP 5.23-1(2): Multi-engine aeroplane operations and training

According to FAR 23.1545 (6) Red line speed is the maximum value of Vmc
CAAP 5.23 -2(2) refers to a Vmca with no definition, or means of determining this speed.
Is Vmca a speed invented by CASA FOI's without reference to the certification speeds?
How does a test pilot determine this Vmca?

There seems to be a significant move by various authorities to close major public infrastructure for surprisingly long durations after accidents.
Seen more often in freeways and rail.

elche: I agree the gear is down and explains why the nose wheel ended up on the Tullamarine Freeway. This is a startling development.

The crash was about 200 metres from my front door, I heard it and was there shortly afterwards. I was in ATC for 42 years and saw a number of accidents/incidents and learned that speculating as to the cause is a complete waste of time. People have asked what happened. My reply is that I don't know, wait for the report.

Well said, Sir.

zzuf,

A previous discussion here on pprune regarding Vmc and Vmc(a)
http://www.pprune.org/tech-log/26280...-vmc-vmca.html

Am I the only one who thinks that the Channel 10 published footage of the aircraft coming in low over the DFO building with the gear down is not actually the incident aircraft? I think it is an aircraft (clearly a B200, and possibly even the same one) landing on RWY35 at another time. I would like to know if Channel 10 actually checked the metadata before they forked out money for that one. The other dashcam footage published showing the fireball from a distance is more believable as the crash aircraft.

Just because a news outlet publishes footage online and says it is the crash aircraft doesn't mean it is.

zzuf,

The reason there's no definition as you observe is that it is defined by ICAO.

That's why.

It's an internationally accepted definition, despite the ignorance of some.

https://en.wikipedia.org/wiki/V_speeds

https://en.wikipedia.org/wiki/Minimum_control_speeds

And even if it is "the" aircraft immediately before "the" tragedy, how can anyone be sure that the gear was not in transit during that short period - that is, extending rather than extended?

Elche
Nothing authoritative there.
It seems that as far as certification standards (FAR's) go there is no such thing as Vmca.
Probably developed in the same way as the myth that Va is always related to Nz max.

zzuf,

Been working in a few countries, and all seem to recognise Vmcg (for on ground) and Vmca (for when airborne). The TOPA we use shows Vmcg as limiter to V1. The flight manuals of Lockheed , Boeing and Airbus aircraft I have flown all show Vmcg and Vmca numbers.

Am I the only one who thinks that the Channel 10 published footage of the aircraft coming in low over the DFO building with the gear down is not actually the incident aircraft? I think it is an aircraft (clearly a B200, and possibly even the same one) landing on RWY35 at another time. I would like to know if Channel 10 actually checked the metadata before they forked out money for that one. The other dashcam footage published showing the fireball from a distance is more believable as the crash aircraft.

Just because a news outlet publishes footage online and says it is the crash aircraft doesn't mean it is.

No not alone, if you look at the fl24 data. was aircraft operating before and after and one landed on the e/w runway from west not long before the accident. The livery is similar to the crashed aircraft, you can work out who that was if not the aircraft involved, I wont name them for fear of misquoting down the track.

As for 1.8nm and 90m seperation, thats a red herring. Come to my place at Carrum and 1k sep and less is quite normal. We had one home built it looked like last week that was at 350 ft doing a circle, verified by laser (not mine).

There are a few sims on youtube of simulations of engine out in this type, they all take 90 seconds at least to attend to.


http://www.pprune.org/images/statusicon/user_online.gif http://www.pprune.org/images/buttons/report.gif http://www.pprune.org/images/buttons/quickreply.gif

https://www.youtube.com/watch?v=JDzi-utoKtc&t=201s

Interesting C90 EFATO video at light weight.
B200 speeds:
Vmca 90
Vx 101
Vy 108

If autofeather is in use reducing power lever before the prop stops will cancel autofeather.

Anyone know if Vmca assumes engine inop is feathered or not?

donpizmeov
Thanks for that, I can find no mention, in the certification standards, of Vmca. Since it seems so widely used there must be an authoritative statement somewhere that says if you establish Vmc as required by the certification standards you can call it Vmca.
As you would know the procedures for establishing aircraft performance speeds are described in great detail in the FAR's and amplified in various AC's.
Anyway this is clearly the wrong place for this discussion so I will desist.

Vmc/Vmca
 

It sure doesn't help when the FAA gets a bit slack (in a few documents, no less) with nomenclature and can't make up their mind as to what's what .. see, for instance, here or here, or even, here or here.

One expects it between the certification and operations folks but it hurts my head when the certification mob over there has difficulty with consistency ....

For what little it might be worth, the first reference (FTG) does say "The VMC (commonly referred to as VMCA) requirements... " in the body text .. and then goes on to adopt the Vmca nomenclature as a general usage. At least AC23-8C is consistent with Vmc.

Would never have happened in the days of Air Liquide House ...... as zzuf would well recall ...

You think?

I've got a lot of Respect for GH but he made comments on the channel 9 news tonight that were akin to something a single engine private pilot would make.

'Modern twin engine aircraft are designed to be able to climb when one engine is failed'

Oh really? Pretty broad statement there. Better off keeping your mouth shut unless you are going to fully explain.

Whilst the investigators are probably up there with the best of them the interference that happens from the politically correct amongst their 'superiors' may see more bull**** like the Norfolk Island lie.

To those of you doubting the Chanel 10 video, look at the YouTube link provided earlier which is to a HD version of the footage, it is also slightly longer. Looks pretty convincing to me.

Steve

Yes, this is my first post, and yes, i once saw a plane, so please take my comments with a grain of salt.

What I see:

With reference to the female witness that reported the aircraft rocking from side to side. Listen very carefully to what she says. Where she was, what she did and what she saw. Anyone remember the chk chk girl. If not google it, in short she was an apparent witness to an incident, turns out she fabricated the whole story.

The footage linked in post #219 is very deceiving, but if you look closely at google earth maps you can see exactly where this car was on Bulla Rd. You can use signs, road markings such as arrows, intersections, trees, guard rails etc etc.

Yes, I understand the car is moving, but the aircraft in the footage grows in size much more than the surrounding objects in the footage. This tells me the aircraft is not only moving left to right but has significant forward movement, towards the car.

Look closely at what appears to be the main gear just before the aircraft goes out of sight. It looks to me like the aircraft crosses Bulla Rd at close to maybe 45 degrees and with the left wing a little low.

edit: chk chk boom girl

Agree. The prang happened right behind the curved signs. That video is of an aeroplane a long way from the curved signs (and heading the wrong way for the prang flight).

Desmotronic, all 3-blade B200s and McCauley 4-blade B200s are certified for Vmca with a windmilling prop.

Hartzell-Raytheon and Hartzell-Raisbeck 4-blade B200s are certified with the inop feathered. That's why on these machines AFX is a mandatory system. If it doesn't work you don't take off.


Yes if you pull a power lever back when AFX is doing its thing you'll disarm the system. That's why the checklist does not direct you to pull back a power lever for an engine failure after takeoff/in flight. And they also have a note at the bottom of that checklist about the AFX being disarmed if you do.