help with interview questions

[player]

I need some help with some interview questions.


1. How do you calculate a VDP


2. Weather associated with a fast moving cold front

3. Weather associated with a warm front

4. what is a dry microburst and can they be found anywhere besides convective activity.


thanks for the help,

player

 

[maverick_fp00]

VDP: Height Above Touchdown divided by Ground Speed

Weather is in front of a cold front, then after cold front passes, winds from the north and clear skies.

Weather with regards to a warm front sucks.... =]

Not very detailed, but I'm in a rush.. maybe I was close.. ??

 

[80/20]

Just curious and have to ask..

What kind of job is the interview for?

Good luck

 

[typhoonpilot]

Player:


1. One way to calculate a VDP is to take the time from the Final Approach Fix to the MAP in seconds and subtract from it the MDA in Height Above Touchdown divided by ten. This is much easier when explaining on a chalkboard. Take the Erie, PA NDB Rwy 6 for example. At 120 knots the time from FAF to MAP is 1:57 or 117 seconds. The MDA is 548 feet above touchdown. So

117
55 ( 548/10 )
-------
= 62 seconds.

62 seconds after crossing the FAF you will be at your VDP. This is a good way to calculate this for two reasons. One, it gives you an idea of how fast you need to get down. On this approach you will need to descend 820 feet in 62 seconds to be in a position to land. Secondly, if you don't see the runway after 62 seconds you will be preparing for a missed approach.

2. A fast moving cold front forces upward motion of the warm air along it's leading edge. If the warm air is moist, precipitation occurs immediately along the surface portion of the front.

3. The weather occuring with a front depends on:
a) The amount of moisture available
b) The degree of stability of the air that is forced upward
c) The slope of the front
d) The speed of frontal movement, and
e) The upper wind flow.

A shallow warm front often causes widespread precipitation, low stratus, and fog.

4. A dry microburst is a small scale intense downdraft usually associated with Virga.


Hope that helps.

Typhoonpilot

 

[trainerjet]

VDP: Height Above Touchdown divided by Ground Speed

I must be missing something. Let me see if I have this straight. Let's say for example, your HAT is 500' and your groundspeed is 140kts (fairly typical of a non-precision approach), 500/140=3.57

Are you suggesting the VDP in this case is 3.57 miles from the runway? Or are you suggesting that you fly 3.57 miles past the FAF to reach the VDP?

From a HAT of 500 feet at a groundspeed of 140 kts, to maintain a nominal 3-degree glidepath, you would descend at 700 fpm for 1.5 miles. I would suggest then, that the VDP be 1.5 miles from the runway, and your descent rate to maintain the 3-degree glidepath would be a factor of groundspeed, i.e. 120 kts = 600 fpm, 150 kts = 750 fpm, etc. Or, if no DME were available, to use the time method recommended by typhoonpilot.

 

[P3tarbaby]

DME Method:

HAT/300 + DME at Threshold

Timing Method:

Timing from FAF to MAP - HAT/10

Reference: Airline Pilot Technical Interviews - A Study Guide, by Ronald McElroy