Pilots on final approach to Reno Airport (RNO) may receive a low altitude alert from Tower, even when the aircraft is established laterally and vertically on an approach procedure; especially during periods of limited Tower visibility (e.g., smoke, haze, etc.).

Low altitude alerts are generated by an automated system commonly referred to as “MSAW” which stands for Minimum Safe Altitude Warning. The MSAW sensitivity under the RNO final approach course was adjusted to more accurately report an aircraft’s altitude during Cold Temperature Compensation. A low altitude alert will most likely be issued to aircraft on an approach to Runways 17, in the vicinity of DISCS, approximately 9 to 11 nautical miles north of the runway.

Towers are mandated to consider issuing a low altitude alert to aircraft as stated in Federal Aviation Administration (FAA) Air Traffic Order 7110.65.

If the MSAW activates and Tower visually observes the aircraft is in a safe position to continue, they are not required to issue a low altitude alert.

If the MSAW activates and Tower is unable to visually observe the aircraft, pilots may receive a low altitude alert followed by an instruction to check their altitude.

After receiving a low altitude alert, pilots should immediately check their altitude and determine if it is safe to continue on the approach; then advise Tower of their intentions.

FAA Order 7110.65 - Paragraph 2-1-6 Safety Alert (excerpt):

Issue a safety alert to an aircraft if you are aware the aircraft is in a position/altitude that, in your judgment, places it in unsafe proximity to terrain, obstructions, or other aircraft.

FAA Order 7110.65 - Paragraph 2-1-6 (excerpt):

PHRASEOLOGY -
LOW ALTITUDE ALERT (call sign),
CHECK YOUR ALTITUDE IMMEDIATELY.

Note - Controllers do not have to issue alternate instructions or inform the pilot of the MVA, MEA, etc. if the aircraft is already on final approach.

Aeronautical Information Manual - Paragraph 4-1-16 Safety Alert (excerpt):

Once the alert is issued, it is solely the pilot’s prerogative to determine what course of action, if any, to take. This procedure is intended for use in time critical situations where aircraft safety is in question.