I just reconfirmed that if you select direct-to the FAF or fly course direct-to the FAF, the GTN series will display the following message at 2 NM prior to the FAF: "Approach Not Active, Do not continue approach". The same happens on the GNS430W/530W and the versions of the G1000 that I have, although the messages are slightly different. I have the Beechcraft G58 G1000 trainer and the Cirrus 22TN with Perspective trainer. They all work the same. The only way I found to obtain guidance on the extended final approach course and not cause the approach to be aborted is to activate the final approach leg, although it doesn't provide the magenta line extending from the FAF.
Also, here in the US, direct to the FAF, straight in, is not permitted if the conditions are IMC. Straight in may not be issued by ATC if the FAF is also an IAF, in which case the pilot must fly the PT. If it is IMC, vectors to final must provide an intercept on the final approach course no closer than 2 NM outside the gate (the gate is typically 1 NM from the FAF) which normally means 3 NM from the FAF.
@bookworm #90 and #92
For operations within Australia the wording of your briefing would be very appropriate. I would like to add that I, personally, would not recommend acceptance of bypassing FAFs in any vectored approaches, including ILS(es). In my experience, I heard of the offers to bypass final ILS fixes only after the crew declared to be "visual".
Sorry, should have made clear that this would be for RNP APCH (GPS approaches).
OK, understood. But I still don't think that the restriction "The final approach trajectory should be intercepted no later than the FAF in order for the aircraft to be correctly established on the final approach course before starting the descent (to ensure terrain and obstacle clearance)" should be made binding for non PRNAV approaches. In PRNAV procedures vectors to the FAF are not allowed anyway.
We have been doing this for years and years (GPS based RNAV approaches have been around for over ten years in this part of the world) and the equipment is perfectly capable of handling vectors to the FAF or close to it. The approach plate of Saarbrücken posted two pages up shows that there are established approach procedures (in Germany at least) that contain an angle towards the FAF. Wether this angle is part of the procedure of the result of a vector issued by ATC should not matter in my eyes.
Not in my part of the world as clearances direct-to the final approach fix are very common for all types of approach (especially for ILS).
Sorry, should have made clear that this would be for RNP APCH (GPS approaches).
May I then ask those with experience of different navigation systems as to whether the following would be appropriate guidance to flight crew in an ops manual?
Not in my part of the world as clearances direct-to the final approach fix are very common for all types of approach (especially for ILS).
May I then ask those with experience of different navigation systems as to whether the following would be appropriate guidance to flight crew in an ops manual?
ATC tactical interventions in the terminal area may include radar headings, ‘direct to’ clearances which bypass the initial legs of an approach, interceptions of an initial or intermediate segments of an approach or the insertion of additional waypoints loaded from the data base. In complying with ATC instructions, the flight crew should be aware of the implications for the navigation system.
‘Direct to’ clearances may be accepted to the Intermediate Fix (IF) provided that it is clear to the crew that the aircraft will be established on the final approach track at least 2 miles from the FAF.
‘Direct to’ clearance to FAF is not acceptable. Modifying the procedure to intercept the final approach course prior to the FAF is acceptable for radar vectored arrivals or at other times with ATC approval.
The final approach trajectory should be intercepted no later than the FAF in order for the aircraft to be correctly established on the final approach course before starting the descent (to ensure terrain and obstacle clearance).
I don't even care if my FMS switches to "APP" or not as this is an RNP5 procedure
I am sure in so far, as our equipment and our operation is officially certified for RNP 5 (= B-RNAV in Europe) only. RNP 1 (= PRNAV) certification is still fairly rare. Of course I know that RNAV final approaches are constructed based on RNP 0,3 capability (ICAO DOC 8168).
The terminology on this can be confusing but the following may help.
Performance Based Navigation specifications come in a number of flavours, with a categorisation between RNP (with on board performance monitoring and alerting) and RNAV (no on board performance monitoring and alerting).
B-RNAV is RNAV 5. There is no RNP 5 specification. P-RNAV is RNAV 1, and is what is required for EHAM. There is an RNP 1 specification, but it is not required at the moment in Europe as ATC monitoring and intervention is sufficient to ensure the level of safety required. The RNP APCH specification has different accuracy requirements in different flight phases. It requires an accuracy of 1 nm, except for final approach where it is 0.3 nm.
As well as an accuracy requirement, there are functional requirements of the nav specs, so neither the airworthiness certification nor the operational approvals are inclusive in the way you might expect. If you are flying GPS approaches (legally) then you do have certification/approval for RNP APCH. But that doesn't mean you have certification/approval for RNAV 1.
The approach under discussion is most certainly not an "RNP 5" procedure. It is designed for a 0.3 nm accuracy on final approach, and you must have the appropriate scaling on your CDI to fly it safely. In your subsequent posts you do show that the FMS has switched to "TRMNL" and "ARPCH", which gives the required sequencing of accuracy.
@what next
Thank you for your informative and detailed posts.
It appears that during the two vectored intercepts (you documented in your post #82) you joined the final(s) after overflying FAF(s). I would have had absolutely no problems accepting such vectoring assistance. It is an offer (so far never received by me) of being vectored (for a LNAV letdown) to the point past the FAF that I would refuse.
I have two more questions, if I may.
At the bottom of that approach plate (Saarbrücken RNAV 09) there is a table of distances from threshold versus altitude (for 2, 3, 4, 5, 6, and 7NM) for a three degree "glideslope".
Do you consider these pairings as defining formal step-down fixes?
Where from could I obtain charts that show relevant MVAs used by the German controllers to vector IFR flights to by-pass FAFs during non-precision approaches?
The graphics are very 'Atari' aren't they?
They do... but the presentation is very clear and uncluttered. A typical airliner EFIS dosen't look much different from ours, not even the new ones. Just more pixels.
How was GPS integrated - a retrofit by Honeywell?
No, this FMS was already built around a GPS sensor from the beginning. GPS has been here since around 1990, that's almostt 25 years.
The graphics are very 'Atari' aren't they?
Is there any certified avionics that looks significantly better?
In my view the G1000 also looks like an eighties video game console, very visible pixels, no antialiasing (not even full pixel AA - in commercial electronics, subpixel AA is state of the art for ten years or so).
