Diagnose this ...

[kgwilson]

9 hours ago, old man emu said:

 

 

As for the half hour to notice that achieved ground speed was not as planned, I said that the pilot was flying a familiar route TIBMIN and enjoying the view.

That just displays poor airmanship.

[old man emu]

Here's a clue: 

The answer can be found by the use of Occam's razor.

 

Occam's razor is the principle that, of two explanations that account for all the facts, the simpler one is more likely to be correct.

 

[RFguy]

alright, I am ready for the next riddle

 

let's have it

[M61A1]

You could get a job writing CASA exam questions OME. 

[rgmwa]

Applying Occam’s Razor leads me to conclude that the simplest explanation is “something’s gone wrong”. However as it’s a minor problem and I know where I am, I’ll just add a few more revs to make up for lost time and enjoy the flight. 

[old man emu]

27 minutes ago, rgmwa said:

the simplest explanation is “something’s gone wrong”.

Getting to the answer! 

What lead you to the plan to add more revs?

 

I was betting that Facthunter would solve this easily.

[old man emu]

1 hour ago, M61A1 said:

You could get a job writing CASA exam questions OME. 

This one's sure exposed a lack of knowledge.

[onetrack]

I think the question is incomplete. It would be helpful to add in the engine type and make, and exactly what instruments are fitted. I'm thinking lower engine power output than expected, but I'm still thinking as to why.

[Thruster88]

4 minutes ago, onetrack said:

I think the question is incomplete. It would be helpful to add in the engine type and make, and exactly what instruments are fitted. I'm thinking lower engine power output than expected, but I'm still thinking as to why.

It can't be a loss of power because the airspeed is correct. Unless the ASI, tachometer and engine all have faults, a one in a million event. I am predicting a disappointing end to the quiz.

[facthunter]

It's not a big enough error to affect the flight unless your planning was very tight. 10% Flight fuel is common in fast planes as a reserve. Could just be insects guts on the prop or tacho error or such. Do your usual monitoring and continue.  Nev

Edited October 15, 2020 by facthunter

[rgmwa]

1 hour ago, old man emu said:

Getting to the answer! 

What lead you to the plan to add more revs?

 

Ground speed less than expected so need to speed up a bit if I want to stick to the plan.

[Blueadventures]

Hose to static ports failure perhaps

[old man emu]

1 hour ago, facthunter said:

Do your usual monitoring

Why? What will that tell you?

[M61A1]

2 hours ago, old man emu said:

Why? What will that tell you?

That if it gets any worse you might actually take a look at the static system and do a leak check and cal your ASI at your next service.

If you consider it enough of a problem, the answer would lie somewhere in the static system or the GPS. Since the GPS is unlikely, that leaves the static system. You can leak check the static system which will lead the a leak in the aircraft plumbing or a fault with the instrument. Depending on the aircraft type the little sleeve on the pitot used to calibrate the static system could have moved.

[old man emu]

6 minutes ago, M61A1 said:

If you consider it enough of a problem

You had better strop Occam's razor, 'cause it's as blunt as.

 

As you are told in all examinations - read the question carefully and think about the information it gives you.

[Downunder]

On 14/10/2020 at 11:00 AM, old man emu said:

 

What actions do you take to diagnose why you are slow and late, and what could be the cause?

Check TAS against ground speed (gps) and determine I have a head wind.

Speed up or accept I'll be a bit late.

[rgmwa]

OK, how about this. Since it's a nice day and I'm not in a hurry, have plenty of fuel. and the missus has fallen asleep, just out of curiosity I'll turn 180 deg and backtrack for ten mins, then do another 180 and resume course.  If I'm not back at my first turning point after ten minutes, I know the wind has come up and I'm flying into it. Therefore nothing wrong with the aircraft. In that case, I can also time how long it takes me to get back to the starting point, use my map to work out the distance (old school), and figure out the wind speed. 

Edited October 15, 2020 by rgmwa

[Blueadventures]

I wouldn't worry too much about things, may be slow down to see what the ASI shows when buffeting starts or do a stall; (at a safe height of course) plenty of holes in swiss cheese and you can usually get way safely flying though a single hole:)

[APenNameAndThatA]

I've got $10 that says that this is going to be nonsense.

[APenNameAndThatA]

If you are maintaining 75% power, like the question says, then it will be wind. I suppose the answer you want is to check for carburetor ice.

[facthunter]

Whether you can safely complete the trip.. Could easily be you have a heavier plane than you thought which will gradually correct the figures as you burn fuel.  I got called away at the time Fits with OME's 3 hours difference  to this  one. Nev

[planesmaker]

If it was carb ice there would be a reduction in revs. GS is outside of aircraft systems. 

[Jase T]

You used a paper map to plan the flight using a ruler and a blunt pencil.. You planned on a WAC and used a Wizz Wheel for the heading and GS calculations. Did you also allow one minute per 1000 feet of climb into your ETI based on a rule of thumb? In flight you used a GPS that was accurate to the second that it was looked at whereas your planning was based on an average for the entire leg... 

[M61A1]

1 hour ago, old man emu said:

You had better strop Occam's razor, 'cause it's as blunt as.

 

As you are told in all examinations - read the question carefully and think about the information it gives you.

Maybe you really should write exam questions for CASA....They are always written in a vague manner with little relevance to the real world.

I won't be giving it any more thought. I have actual things to fix.

[Ando]

23 hours ago, rgmwa said:

You are flying lower than the altimeter is reading so your indicated airspeed is higher than than you expect you TAS to be for your  planned altitude so you are slower over the ground than you anticipated.

Good answer !