Descent Below MSA

Question 1

Minimum Operating Altitude never less than?

Answer 1

Night or IMC; the Relevant MSA
OR if under Radar Control, not < Radar Cleared Altitude

VMC;
- 500ft above all obstacles

Question 2

Explain the Strong Wind Adjustment.

Answer 2

When the wind exceeds 50kts increase the MSA by 2,000ft.

Question 3

What is the correction to MSA when flying in Mountain Wave conditions?

Answer 3

The height of the ridge above the surrounding terrain.

Question 4

When is VMC descent below MSA allowed by DAY?

Answer 4

If flight can be continued to ensure clearance from all obstacles on the intended track.

Question 5

When is VMC descent below MSA allowed by NIGHT?

Answer 5

Only if line of sight is also line of flight.

Question 6

What is the maximum RoD within 3,000ft of MSA?

Answer 6

3,000fpm

Question 7

What is the minimum allowed Radar Cleared Altitude? What bandwidth?

Answer 7

1,000ft, ±5nm.

Question 8

What is MGA?

Answer 8

Minimum Grid Altitude. Lowest safe off track altitude in a specified grid

Question 9

What is MTCA?

Answer 9

Minimum Terrain Clearance Altitude. The minimum safe altitude along a procedural track (and up to 5nm either side). Numbered in RED.

Question 10

What is MEA?

Answer 10

Minimum Enroute Altitude. Lowest usable altitude ATC for a given route segment. MTCA always trumps this figure.

Question 11

What is MSA?

Answer 11

Minimum Sector Altitude. Minimum Safe Altitude for a specified section of a prescribed circle, normally 25nm.

Question 12

What is TAA?

Answer 12

Terminal Arrival Altitude. For RNAV/RNP Procedures only.

Question 13

How can you justify descent below MSA?

Answer 13

• Procedurally
• Visually
• Radar Control