PBN Questions

Question 1

What is a 3D approach?

Answer 1

An approach flown fully managed.

Eg RNAV using VNAV minima
Or LNAV minima if the only one available

Question 2

What is a 2D approach?

Answer 2

An approach flown using selected vertical guidance.

Question 3

If GPS PRIMARY is lost do you have to get re-cleared or cancel the approach?

Answer 3

Not necessarily.

If you lose GPS PRIMARY on one OR both sides IF the approach has multiple nav sources you can continue. You just need to monitor RNP vs EPE and the onboard monitoring will tell you if you are unable to continue.

As long as RNP < EPE you’re ok.

Question 4

On an RNAV approach with LNAV or VNAV minima when would you discontinue the approach?

Answer 4

1. GPS PRIMARY lost on BOTH NDs
2. Xtrack error > 0.3nn
3. VDEV bar > 3/4 dot (or 75ft VNAV only)
4. NAV FM/GPS POS DISAGREE
5. NAV ACCUR DOWNGRADE on BOTH FMGCs

Question 5

When are you ‘unable RNAV due equipment’?

Answer 5

1. Loss of Nav mode (so no CLB)
2. Map shift
3. NAV FMS1/FMS2 POS DISAGREE
4. NAV FM/GPS POS DISAGREE (ECAM)
5. NAV ACCUR DOWNGRADE on BOTH FMGCs
6. Loss of the only specified nav source
7. On RNP1, Xtrack > 0.5nm