Whizz wheel question?
 

Help!

I'm revisiting a couple of old ATPL questions to settle a bet (Many beers involved if I win!!):)

I've plain forgotten how to work out TAS given a mach number, a level and a temp; on the whizz wheel. Can anybody refresh my memory.

Thanks

ooops btw whizz wheel is a Jepp CR2.

May the liquid amber flow
 

twentyelevens

I've just recently did flight planning and it is still fresh in my mind.

If you have current Treu OAT then line that up with the DOUBLE ARROW mach index in the true airspeed window.

ie temp -46 then place the arrow on it, then read from inside grey scale as Mach No, ex if M0.8 then 80 on grey to the outside scale which willl be your TAS. Roughly 480 Kts.

If you have an indicated OAT ie -4 for FL310 (pretty warm) then line up the Mach no with the small arrow. Use the green rotating lie CT 1.0 and line it up with the spiral line in the Mach No window and read your TAS from that. Again with a M0.8 and IOAT of -4 TAS should roughly be 481 Kts.

Hope this helps
And enjoy:ok: :ok: :ok:

ITS

While on the wizz wheel topic...

Whats the trick to work out an adjusted apprach minima given a reduced missed approach performance gradient?

...Disco

I'll give it a go in explaining it. :\

Missed approach gradient: 2.5%
Find out what percentage your aircraft can do from flight manual. Let's call it 1% for argument sake.

Line up 25 on outer scale with 10 on the inner.

Now here's the tricky bit. Figure out the altitude that you have to climb from MDA to MSA/LSALT etc. Eg) MDA: 500ft, MSA: 2000ft. Therefore 1500 ft to climb.

Find 15 on the outside and read the number on the inside...which is 6. This means that with an engine out you'll only be able to climb 600ft. Therefore you'll be 900ft (1500-600) below the altitude you should be.

Add this deficit....900ft to your minima to get your new MDA/DA. In this case 1400ft.

You'll get much quicker with a few examples on your own. It's also an extremely good idea to have an approximate engine out percentage climb gradient as there won't be any time to fiddle around with a flight manual should it happen while you're up there,

The other option available is to declare an emergency and continue to the original MDA or below it.

If anyone finds an error with the above, please feel free to correct me. :8

choice bro
 

yeeeh, nah

you boyz know how to use a whizz wheel ? let me show yu how to yuz a whizz wheeel !!!!! (during a Kendell interview)

:} :} :} :}

1,500 - 600 = ?

Someone had to do it....

But seriously - that's a neat technique which I'll have to file away.:ok:

Ahh bugger! I knew I'd screw something up at tha time of the night. I'll change my equation now. :eek: