BeechTalk - BT - Travel Air—>Baron—>MU2—>Citation

Username Protected · **Posted:** 15 Jun 2019, 23:49

Username Protected wrote:

I know the PC-12 does have accelerated stop distances published in the POH.

Seems so:

Attachment:

pc12-accel-stop-1.png

Seems kind of useless, in what way would you use the chart? There's no decision to be made if the engine quits. So can you think of an example where the pilot knowing the accel/stop distance is useful?

Mike C.

Username Protected · **Posted:** 16 Jun 2019, 00:04

Username Protected wrote:

So can you think of an example where the pilot knowing the accel/stop distance is useful?

Mike C.

Runway length/airport choice in initial flight planning.

Username Protected · **Posted:** 16 Jun 2019, 00:29

Username Protected wrote:

So can you think of an example where the pilot knowing the accel/stop distance is useful?

Runway length/airport choice in initial flight planning.

Username Protected · **Posted:** 16 Jun 2019, 00:33

Username Protected wrote:

I know the PC-12 does have accelerated stop distances published in the POH.

Seems so:

Attachment:

pc12-accel-stop-1.png

Seems kind of useless, in what way would you use the chart? There's no decision to be made if the engine quits. So can you think of an example where the pilot knowing the accel/stop distance is useful?

Mike C.

Username Protected · **Posted:** 16 Jun 2019, 01:05

Username Protected wrote:

Alternator failure, failed AHRS or blanked PFD. Lots of failures are possible that may or may not be safe to abort.

If those failures happen 1 knot above decision speed, then you are flying anyway and have to handle those failures in the air just off the runway. Meeting accel/stop doesn't change that reality.

Mike C.

Username Protected · **Posted:** 16 Jun 2019, 01:21

Username Protected wrote:

Do you have the big batteries in the mits?

Two 24v Concordes. I think each has about 42 amp-hrs.

Username Protected · **Posted:** 16 Jun 2019, 05:06

Username Protected wrote:

It’s a good idea to brief the accelerate stop distance on runways that are close.

Agreed, there are numerous situations to abort a take off besides and engine issue. I’m surprised it’s being questioned (or maybe not...)

Andrew

Username Protected · **Posted:** 16 Jun 2019, 06:10

Username Protected wrote:

It’s a good idea to brief the accelerate stop distance on runways that are close.

Agreed, there are numerous situations to abort a take off besides and engine issue. I’m surprised it’s being questioned (or maybe not...)

Andrew

Username Protected · **Posted:** 16 Jun 2019, 07:21

Username Protected wrote:

Alternator failure, failed AHRS or blanked PFD. Lots of failures are possible that may or may not be safe to abort.

If those failures happen 1 knot above decision speed, then you are flying anyway and have to handle those failures in the air just off the runway. Meeting accel/stop doesn't change that reality.

Mike C.

Username Protected · **Posted:** 16 Jun 2019, 07:24

Username Protected wrote:

It’s a good idea to brief the accelerate stop distance on runways that are close.

Agreed, there are numerous situations to abort a take off besides and engine issue. I’m surprised it’s being questioned (or maybe not...)

Andrew

Username Protected · **Posted:** 16 Jun 2019, 08:25

Username Protected wrote:

Do you have the big batteries in the mits?

Two 24v Concordes. I think each has about 42 amp-hrs.

Username Protected · **Posted:** 16 Jun 2019, 09:43

Username Protected wrote:

About 20 hrs in it now. I feel comfortable in it.

That's unusually fast, perhaps a bit of overconfidence.

There's a lot you don't know yet. Try not to get too much of an education at any given moment.

The MU2 is not hard to fly, but it is very unforgiving of inattention and sloppiness. Everything happens fast, so make sure you fly the plane and not that the plane flies you.

Mike C.

Username Protected · **Posted:** 16 Jun 2019, 10:54

Username Protected wrote:

If you don’t have accelerate stop distance then how do you know when it’s safe to abort for an abnormal such as oil pressure, engine fire, door light, etc?

The chart doesn't actually give you that information.

It tells you what distance is required for one particular condition. The chart example is 65 knots and 2500 ft. If you are on a 8000 ft runway, you can stop well past 65 knots, or even after being airborne, but how much past? Chart doesn't say, so you have to judge that as every single engine pilot does already, by look and feel. If you have an engine fire at 66 knots, 1 knot past the decision speed, it would be stupid to fly and not abort on such a long runway, so the chart distance is no special point of consideration.

Quote:

Typical PC12 takeoff briefing includes aborting takeoff for any abnormals before rotation. Accelerate stop gives me one more assurance to safely make that happen. If accelerate stop distance is longer than the active runway, I’ll pick another runway or take on less fuel.

So if you at a 2400 ft runway under the chart example conditions that say 2500 ft is accel/stop, you would not fly?

That's kind of silly when you think about it. A 2500 ft runway gives you about 1 second more time than a 2400 ft runway in which you can decide to stop and still do it on the available runway. Is that 1 second so valuable you wouldn't fly? Why is the next second you would get on a 2600 ft runway not as important to your safety?

The accel/stop distance is an arbitrary number. There's no meaningful change in safety when the runway meets it, unlike a multiengine airplane.

Mike C.