Tricky IFR Questions At Interviews
 

What are some tricky IFR questions that you have been asked in interviews.
It would be nice to hear some questions that people have had trouble with in interviews.

Or on the other hand what are some good questions?

What are the rules for descending below LSALT at night from FL140 in an unpressurissed, 5 seat, single engine, day VFR category aircraft, carrying 8 passengers, 2 opened cans of Avgas and 3 active fuses of gelignite?

I'm not sure if it's in the AIP's or CAO's. Let me know if you find it:D

Are you looking for OZ or NZ IFR interview questions?

maimly looking for Oz questions, anything would be handy

Reaching the minima on the ILS how do you tell if you have 800m, 1.2k or 1.5k vis?

When calculating ROD req'd for a 3 deg slope why do you add the 50'? ie 5 x GS + 50. eg GS 150kt means 800 fpm req'd.

Further to the Messiah's first question...

How do you determine you have the published circling visibility for your catagory of aircraft after an arrival, and how was this number calculated in the first place? No HIAL to help you out with this one.

How about Temperature correction for ILS Glidepath/OM check height for say ISA+20 at 1500'?

Requirements for using Special Alternate wx minimas, including instrumentation AND the other stuff?

I am sorry, but are you going to make a temp correction at ISA+20?

Don

Temperature correction at the outer marker, and for ISA +20? come off it!

It is only a gross error check at best anyway and I wouldn't encourage tying yourself up with mental arithmetic at that point during the approach. I accept making a temp correction to the MSA in extreme cold but ISA +20 is not going to cause a problem is it as your true alt would be higher than your altimeter reading.

Messiah,

Agree with yourself and donpizmeof... I wouldnt be sparing much brain bandwidth to calculate out ISA+20 at the outer marker either, however the original thread started by Gateway customer was tricky IFR questions asked in INTERVIEWS.

Good topic too.

my 2 cents worth...

regarding the 50 ft, i am not too sure but it is either because the ILS glideslope is supposed to bring u 50 ft above the threshold, or since its a precision approach, 50 ft has been added for the PEC.

and from night pistol, if its an IFR flight, then if my memory serves me well, you can only descend below the LSALT within the circling area, which for Cat A, is 1.68 nm from the runway threshold. apart from that, the usual requirements: clear of cloud, in sight of runway, min 5 km vis. ref: AIP ENR 1.5

overmars

It is neither, and furthermore you don't apply PEC in a 747 yet it is still 5x GS + 50'.

It is in fact basic trigonometry, which would take too long to type here but SOHCAHTOA explains it. Remember that?

PEC
 

Overmars,

I reckon PEC is a "one off" 50' amendment.

If we are talking about ROD calculations on a 3deg slope, and if you're adding 50' to the result after 5GS, it would result in a 50 foot per minute increase to your ROD during the approach rather than increasing MDA's, which have no bearing to your ROD calculation.

Me think that the 50' addition to the ROD calculation allows for a more exact profile, i.e. 3.3 degrees.

This of course assuming a fairly typical range of approach ground speeds, for example 120 - 170kts, so CAT B & C, perhaps. If your APP GS is any greater, you may find you have to add more than 50fpm to your ROD calculation to achieve the 3.3 degree slope.

Does this sound feasible or have I had too many jellycups??

520.

TCH...............

The maths...

Example 1. G/S 150 kts = 912000 ft/hr (roughly) = 15200 ft/min. That is your horizontal speed.

To achieve 3 degree profile... which is 5 percent... which is 1 in 20, you need 760 ft/min vertical speed.

Or done the quick way, 150 * 5 = 750 fpm.

Example 2. G/S 100 kts = 608000 ft/hr (roughly) = 10133 ft/min.
Again, to achieve 3 degree profile, 5 percent, 1 in 20..., you need 506 ft/min vertical speed.

Or in your head quickly... 100 * 5 = 500 fpm.

Never heard of applying an extra 50 fpm to the calculation, so that's my answer in an interview scenario... and I couldnt fly that accurately if I tried anyway. Gotta use this one as a rough guide for a ballpark figure... I got other things I got to look at in my scan!



Now surely there must be more useful questions that people have been asked in interviews during their careers???

I'm not an IFR driver heres my view of things for those who care

The Maths:
TOA
tan(3)=ROD/GS
tan(3)*GS=ROD (knots)

Theres 1852 m in a nm, and 3.281 ft in a m so nm > ft is *6076.412 and of course hours to minutes is *60.

So converting knots to fpm is 6076/60 = 101.2735

tan(3)*101.2735*GS=ROD
tan(3)*101.2735 = 5.307
So all that crap means that for a 3 degree approach GS*5.307 gives required ROD, so why is 50 ft added? possibly to account for the .307 but then again could be wrong.

My 2c

DME gives slant range speed as GS, not 'true' ground speed. So you'd have to use sin not tan if using DME. Not that it makes much difference - I get the same answer as you Pilot steve.

So tell us Messiah - is we right?

I reckon it's probably to make it a tad more accurate. My brain finds it easier to halve my groundspeed then add a zero rather than multiplying by five. Isn't that what most people do? Same result....just seems easier.

"Keep it simple stupid"

Some good fellow tought me that many moons ago, I still live by it today. I'm with you cjam

I am planning an IFR flight to a destination with an instrument approach chart with the minima titles shaded gray. A colleague of mine told me that if I use the QNH on the aerodrome TAF, I do not have to increase the minima altitudes by 50 ft. Sounds good. But if en route, ATS informs me of the Area QNH, do I use the Area QNH for the approach and increase the minimas by 50 ft, or do I stick to the TAF QNH and leave the minimas as it is?

Hope someone could help me out here.

Thanks.

If you have a local NH you follow the altimeter setting rules and set local NH at the top of descent and leave the minimas as they are. You're only reuired to add 50ft to the minimas if you use the area NH, which you wouldn't do if you have one from the TAF.

The shaded box means nothing unless you have an actual NH - which must be obtained from an ATIS, AWS or AWIS.

...and for those who haven't noticed, a certain key on my keyboard is broken dammit!!