Use of GPS on a (JAA) CPL Skill test

[Keygrip]

I read that a recent FE(CPL) seminar at Gatwick was going to include the topic of what use a CPL candidate could make of a panel mount GPS.

Can anybody share some of the details - how much info is allowed, and what, specifically, is NOT allowed to be used?.

[Say again s l o w l y]

From my understanding, a candidate can use the raw data from a GPS, Lat and Long, but that's all. None of the navigational features; moving map, GOTO etc..

[idle stop]

I've just been reading through a copy of the Helicopter FE's Debrief Note. No specific mention.
My understanding, as regards rotary wing, is that GPS and other Navaids are No-No for the planned and track crawl legs, but for a practice diversion the candidate should use available aids to assist in refining the initial (MDR) plan. This demonstrates a) working knowledge of equipment in aircraft and b) ability to cockpit manage/division of attention/prioritisation.
Can't see anything wrong with this principle for the 'planks'.

[Long Briefing]

I believe the situation is as follows:

Firstly I assume you are referring to the IFR diversion leg of the nav where you have to fix your position.

As GPS may not be used as the primary means of navigation when IFR - there's a pink AIC about this - you must get you position fix from classic aids such as VDF, ADF, VOR and DME. It is only when these are not available due to range, low level, maintenance periods, etc that the GPS can be used. When GPS is used you may only used raw data to determine your position. You may not use Lat/Long as that is your position! Nor can you sneak a peek at the map display! Raw data is taken to be a plot of range and bearing from a selected waypoint.

At other times, when you are not in the navigation part of the test, you can use the GPS in any way you like. A good example would be in the GH section if an emergency was simulated where an emergency diversion to the nearest airfield was required. Here the GPS can help you determine the closest airfield, help you track to it and even tell you the R/T frequencies you need. If it helps expedite the diversion it is good airmanship to use all the tools at your disposal.

Lastly, don't take my word for it. Why not telephone the CAA examiners and ask. After all, we pay the CAA enough in fees so why not use the service? I have always found them to be friendly and approachable.

Good luck with your CPL skill test!!

[Keygrip]

Thanks for the meaty answer, L B.

Why not ask the CAA?? That would not generate questions and answers from oodles of instructors and examiners.

Interestingly enough, one of the CAA examiners told me that Lat/Long from the GPS (or Loran) was perfectly acceptable for the diversion section of the navigation.

Same examiner also told me that, if the aircraft was suitably equipped (RNAV - KNS80 for example) it was perfectly acceptable for candidate to move a VOR to the diversion and then track direct to it.

I'm curious now about an Arrow I flew recently - had two Garmin 430 GPS's on board. One click of the buttons would give me a page of the SIX nearest VOR's (or whatever) - with frequency, ident, bearing and distance.

None of these were identifiable through morse code idents on the audio panel - you just have to believe them to be accurate. So, if you are going to believe the GPS derived distance, why not believe the GPS derived radial/bearing and accept the information without identing the same stations on the VHF section of the receiver.

If you DO ident the station, through the VHF portion, and the CDI/HSI (whatever) gave you a different reading than the GPS screen, which do you believe?? The digital, accurate, GPS radial/bearing or the not so hot, moving, selectable CDI/OBS indicator on an HSI that doesn't slave 100% accurate with the equally unreliable magnetic compass?

Also wonder about the aerials/antennae on that aircraft. I don't remember seeing a VOR (wire coat hangar style) aerial on the tail - but did see ONE VHF and TWO GPS antennaes on the roof.

Does that suggest that the two VHF (speech) transceivers are fed through a combined antennae, and does that single antennae also get the VOR signal - or do the two standard VOR indicators receive their signals from GPS derived data - in which case GPS actually IS the primary means of navigation - but displayed in a conventional way?