# Quick Answer: What’S The Difference Between AGL And MSL?

## Can you fly IFR without a transponder?

You do not need a transponder to fly IFR, as long as you stay outside of airspace that requires it..

## What does above ground level mean?

AGL, or above ground level, is the distance that an object is above the ground below it. For example, if you are standing on the roof of a building that is 100 feet tall, you are at 100 feet AGL. MSL, or mean sea level, refers to the distance an object is above sea level.

## How is MSL calculated?

The mean sea level (MSL) is determined by continuously measuring the rise and fall of the ocean at “tide gauge stations” on seacoasts for a period of about 19 years. … Because we cannot directly see the geoid surface, we cannot actually measure the heights above or below the geoid surface.

## Does altimeter read AGL or MSL?

A plane that flies at 10,000 feet MSL and stays level registers as flying at 10,000 feet MSL — no matter the terrain changes below the pilot. Pilots use altimeters, which measure the AGL, when the aircraft is flying at relatively low heights landing at an airport.

## How do you calculate AGL?

Sectional charts normally show both mean sea level (MSL) and above ground level (AGL) heights for towers. Next to the tower, you’ll see two numbers. The top number is the height in MSL and the bottom number — in parentheses — is the height of the tower in AGL.

## What is QFE and QNH?

QNH differs from QFE, which refers to the altimeter setting that will cause the altimeter to read the height above a specific aerodrome or ground level, and therefore read zero on landing. … In most parts of the world, QNH is given in hectopascals (described as millibars in the past).

## Can you fly over Class C airspace without a transponder?

You are NOT required to have a transponder installed for flight UNDER a shelf of a Class C airspace. … There is also an exception to this rule: If your airplane WAS NEVER equipped with an electrical system, you can operate inside the mode C veil, under the shelf of a Bravo airspace area.

## Is airspace AGL or MSL?

ATC is responsible for aircraft separation in Class A airspace. Class E airspace is from altitude 1200 feet Above Ground Level (AGL) up to 18,000 feet. All airspace from 14,500 feet (MSL) to 18,000 feet (MSL) is Class E.

## What does feet MSL mean?

Mean Sea LevelAverage height of the surface of the sea for all stages of the tide over a 19-year period. NOTE: when the abbreviation MSL is used in conjunction with a number of feet, it implies altitude above sea level (e.g., 1000 feet MSL).

## What airspace requires a transponder?

Required for all aircraft in Class A, B and C airspace. Required for all aircraft in all airspace within 30 nm of an airport listed in appendix D, section 1 of Part 91 (Class B and military) from the surface upward to 10,000 feet msl.

## Can you fly over Class D airspace?

Since Class D airspace is controlled to the surface, you can request a Special VFR (SVFR) clearance when weather conditions are below the standard minimums. … To operate SVFR after sunset, you must be qualified for instrument flight under FAR 61, and your aircraft must be equipped for instrument flight.

## Can I fly without a transponder?

In the US if you are flying in Class G airspace or Class E below 10,000 feet you are not required to have a transponder. … One exception to the transponder rule is that if you are flying an aircraft that was certified without an electrical system.