Minimum Turning Altitude

AIM ¶ 5-3-7 — Minimum Turning Altitude

AIM 5-3-7 explains Minimum Turning Altitude (MTA): why it exists, how it's charted, and how pilots comply during turns at fixes above 10,000 ft MSL.

In Plain English

Minimum Turning Altitude (MTA) addresses a gap in obstacle protection that can occur when an aircraft turns over a fix, NAVAID, or waypoint at or above 10,000 ft MSL. At those altitudes, true airspeeds are higher and turn radii are larger, so the standard MEA may not protect against terrain or obstacles in the expanded turning area — especially in mountainous regions.

When a higher altitude is needed for the turn, the FAA publishes an MTA. On government charts it's marked with the MCA "x" flag icon plus a note such as: MTA V330 E TO V520 W 16000.

Key pilot responsibilities:

Be at or above the charted MTA no later than the turn point.
Maintain the MTA until established on the centerline of the ATS route after the turn.
After rejoining the centerline, the normal MEA/MOCA governs minimum altitude.

An MTA can also prohibit a specific altitude or range (e.g., 10,000–11,000 ft MSL) during the turn — altitudes above or below that band may still be usable if MEA/MOCA is satisfied. Recognizing MTA notes during flight planning is essential to avoid inadvertent terrain conflicts.

AIM Source Text

FAA AIM ¶ 5-3-7

5-3-7. 5-3-7. Minimum Turning Altitude (MTA) Due to increased airspeeds at 10,000 ft MSL or above, the published minimum enroute altitude (MEA) may not be sufficient for obstacle clearance when a turn is required over a fix, NAVAID, or waypoint. In these instances, an expanded area in the vicinity of the turn point is examined to determine whether the published MEA is sufficient for obstacle clearance. In some locations (normally mountainous), terrain/obstacles in the expanded search area may necessitate a higher minimum altitude while conducting the turning maneuver. Turning fixes requiring a higher minimum turning altitude (MTA) will be denoted on government charts by the minimum crossing altitude (MCA) icon (“x" flag) and an accompanying note describing the MTA restriction. An MTA restriction will normally consist of the air traffic service (ATS) route leading to the turn point, the ATS route leading from the turn point, and the required altitude; e.g., MTA V330 E TO V520 W 16000. When an MTA is applicable for the intended route of flight, pilots must ensure they are at or above the charted MTA not later than the turn point and maintain at or above the MTA until joining the centerline of the ATS route following the turn point. Once established on the centerline following the turning fix, the MEA/MOCA determines the minimum altitude available for assignment. An MTA may also preclude the use of a specific altitude or a range of altitudes during a turn. For example, the MTA may restrict the use of 10,000 through 11,000 ft MSL. In this case, any altitude greater than 11,000 ft MSL is unrestricted, as are altitudes less than 10,000 ft MSL provided MEA/MOCA requirements are satisfied.

Oral Exam Questions a DPE Might Ask

Q1What is a Minimum Turning Altitude (MTA) and why is it published?

Per AIM 5-3-7, an MTA is a higher minimum altitude required when turning over a fix, NAVAID, or waypoint, because at 10,000 ft MSL or above, increased airspeeds expand the turn area and the published MEA may not provide adequate obstacle clearance — particularly in mountainous terrain.

Q2How is an MTA depicted on government charts, and how would you interpret an MTA notation?

Per AIM 5-3-7, an MTA is shown using the MCA 'x' flag icon with an accompanying note. The note lists the ATS route into the turn, the ATS route out of the turn, and the required altitude — for example, 'MTA V330 E TO V520 W 16000' means 16,000 ft is required when transitioning from V330 eastbound to V520 westbound.

Q3When must you be at the MTA, and when may you descend to the MEA?

Per AIM 5-3-7, pilots must be at or above the charted MTA no later than the turn point and must maintain that altitude until established on the centerline of the ATS route after the turn. Once on the new centerline, the MEA or MOCA again determines the minimum altitude available.

Related Paragraphs in AIM Chapter 5

¶ 5-3-1

ARTCC Communications

¶ 5-3-2

IFR Position Reporting

¶ 5-3-3

IFR Additional Reports

¶ 5-3-4

Airways and Route Systems

¶ 5-3-5

Airway Course Changes

¶ 5-3-6