VOR question

[AVIATROZ]

Q. assuming the maximum likely error in vor to be 5.5*,what is maximum distance apart that beacons can be situated on the centre line of a UK airways in order that an aircraft can guarantee remaining within the airways boundary?
a. 54.5 nm
b. 109nm
c. 66nm
d. 132nm

plz someone explain why the answer is 109 nm ........what the logic behind this question

thanks for help

[focault]

I think that since an airway width is 10 NM each side of its centerline, at 109 NM from a VOR you could be on the correct course to it and being on the edge of the airway corridor.
Formula should be 10NM/tg5,5° that give 104 anyway.

[gAMbl3]

airway width is 5nm of centre line

http://imageshack.us/photo/my-images/192/vorv.jpg/]http://img192.imageshack.us/img192/1696/vorv.jpg[/URL] Uploaded with ImageShack.us (http://imageshack.us)

tan 5.5 = 5nm / dist from VOR 'AX'

AX = 5/tan 5.5
= 5/0.096
= 52.08

So total dist = 52.08*2 = 104.16 nm

or you can use 1 in 60 rule

[AVIATROZ]

can anyone plz confirm with regards to width of the airway......should i use 5nmor 10nm either side...
thanks

[Capt.Morrgan]

5 nm either side of center line. Btw applying 1 in 60 rule gets you exactly 109 nm.
- M

[AVIATROZ]

Q: inbound on radial 090, pilot rotates OBS 10deg left and turns A/C to right and notes the time. While maintaining constant hdg it is noticed that CDI is centred in 8mins. consider nil winds based on this you can conclude that time to station will be?

[FlightDetent]

Depends on the intercept angle, wouldn't it?