Lost Comm routing and VDPs

[kevmor99]

So in 91.185 for lost comms it says "In the absence of an assigned route, by the route that ATC has advised may be expected..." In talking with someone else, they thought when you lost comms and had received a clearance such as "Direct ABC, expect direct DEF in 10 minutes", that you would fly direct DEF after waiting out the 10 mins. This isn't correct, since you already received your assigned route, right?

Also, in calculating a VDP by using HAT/300, on some approaches, such as the APC VOR RWY 16 (attached), I get something other than what they show for the VDP (I get about 2.5 DME?)... I even used the 3.2 glide path angle...

 

[flyingron]

The reg says nothing about waiting ten minutes. It says fly the route you were cleared for or one you were told to expect or one you filed.

The charted VDP isn't necessarily 300' above the threshold. 300 is just an approximate value that people use to make ad hoc VDPs when not charted.

 

[S Joslin]

Use the "Avenue F" (AVEF) acronym for lost comms concerning route of flight...
Assigned, Vectored, Expected, Filed
For altitude, use the MEA acronym...
Minimum en-route, Assigned, Expected

Concerning the VDP, sometimes there are other factors involved as to why a VDP is used such as an unlit obstacle or terrain...

 

[Gucci Pilot]

I'd fly to ABC for 10 mins then go to DEF. There is a reason the controller doesn't want you to go direct to DEF at the present time. The formula they use to calculate the VDP is a bit more complicated than HAT/GS. They also use the VGSI angle or the specified descent angle.

 

[aterpster]

So in 91.185 for lost comms it says "In the absence of an assigned route, by the route that ATC has advised may be expected..." In talking with someone else, they thought when you lost comms and had received a clearance such as "Direct ABC, expect direct DEF in 10 minutes", that you would fly direct DEF after waiting out the 10 mins. This isn't correct, since you already received your assigned route, right?

Also, in calculating a VDP by using HAT/300, on some approaches, such as the APC VOR RWY 16 (attached), I get something other than what they show for the VDP (I get about 2.5 DME?)... I even used the 3.2 glide path angle...

If you want to get into it, the VDP criteria are in FAA Order 8260.3B, Chapter 2, otherwise just accept a charted VDP as being correct.

 

[luvflyin]

So in 91.185 for lost comms it says "In the absence of an assigned route, by the route that ATC has advised may be expected..." In talking with someone else, they thought when you lost comms and had received a clearance such as "Direct ABC, expect direct DEF in 10 minutes", that you would fly direct DEF after waiting out the 10 mins. This isn't correct, since you already received your assigned route, right?

Also, in calculating a VDP by using HAT/300, on some approaches, such as the APC VOR RWY 16 (attached), I get something other than what they show for the VDP (I get about 2.5 DME?)... I even used the 3.2 glide path angle...

Did you receive and acknowledge the "Direct ABC, expect direct DEF in 10 minutes" and then go NORDO? Or did you hear it and became aware that you were Reciever only when you tried to read it back? Exactly when did "lost com happen. I'm assuming you're in Radar Contact here. If you make the turn direct to ABC then your anticipated action should be Direct DEF in 10 minutes.

 

[flyingron]

Actually the 7110.65 does make provision for the controller to ask the party to ident or making turns to acknowledge. I was on board a plane that had a total electrical failure and also a dying battery in the handheld, and through turns we were identified and cleared to come back into IAD and land (we had been in the middle of an IFR approach to GAI).

One lost comm is detected, the rules for expecting times goes out the window. The controller will expect you to go via the listed route options (cleared, told to expect, filed) at the altitudes (highest of cleared, MEA, expect, filed...) without delay.