Clarification on SPEC VIS

[radarbeam]

Hey guys,

I am about to go write my INRAT and I am getting contradictory info on a/c categories for SPEC VIS. so, at the risk of getting shot down, allow me ask you the IFR gurus one simple question.

Are aircraft categories for SPEC VIS departure are based on groundspeed or indicated speed? Harvsair online is telling me to use indicated and Daunless soft app just failed me for using indicated!!! Argh!

My gut feeling is to go with groundspeed, as a headwind can change your spec vis pretty significantly...but I certainly can be wrong!

Thanks!

[eeeroger]

I would go with groundspeed exactly for the reason you stated.

[ThatArmyGuy]

+1

[zulutime]

Groundspeed it is...

[Big Pistons Forever]

Page 16 of the CAP GEN ( new approach plate format) "Take-off Minimums" , which states that

quote

....pilots must comply with the Specified Take-off Minimum Visibility (SPEC VIS) corresponding to the aircraft category listed below (See Approach Chart Legend-Minima Box- for category speed ranges )

Unquote

So we go to page 65
" Instrument Approach Procedures" and see


Quote

The appropriate aircraft Category are determined by the pilot based on the airspeed at which the aircraft is to be maneuvered.

Unquote

[Oxi]

How exactly does groundspeed have an effect on spec vis? Regardless as BPF stated with a source its the manoeuvre speed (IAS).

[trampbike]

It's the IAS, as BPF pointed out.

[DanWEC]

Mistakes do happen with these trainers, but are you sure you read the question right? Definately KIAS for category. GS is for approach FPM and time. Should send a Dauntless an email about that.

[radarbeam]

Thanks for the feedback guys! I went back and verify and all dauntless Q's on SPEC VIS mention using GS to determine aircraft category so I fired them an email.

BTW I passed the INRAT today with a 92%, I'm pretty happy! The GF will be paying me a beer tonight too!

[ahramin]

Just curious, if it was groundspeed, how would you determine that when you are sitting on the ground trying to figure out if you are legal to depart?

[rxl]

Exactly. You only have limited control on groundspeed.

[DanWEC]

92% is an excellent mark! Congrats.

[pelmet]

Groundspeed doesn't make sense. Imagine a circling approach. What is your groundspeed if there is any wind. It will be frequently changing as you turn.

[DanWEC]

You're supposed to pull out your e6b and map, and calculate your GS during the circling. Sheesh, some people don't remember anything from training.

[Rookie50]

Thanks for the feedback guys! I went back and verify and all dauntless Q's on SPEC VIS mention using GS to determine aircraft category so I fired them an email.

BTW I passed the INRAT today with a 92%, I'm pretty happy! The GF will be paying me a beer tonight too!

Smokin...well done.