Decision Altitude (DA)

Definition

Decision Altitude (DA) is the specified altitude (MSL) on a precision or APV (Approach with Vertical Guidance) instrument approach at which the pilot must make a decision: either continue the approach and land if required visual references are in sight, or initiate a missed approach if they are not. It is also referred to as Decision Height (DH) when measured above runway threshold elevation (AGL).
DA is used with approaches like ILS, LPV, LNAV/VNAV, and RNP AR.

Purpose

Define the point of decision-making during a precision approach
Ensure obstacle clearance while providing vertical guidance to the runway
Improve approach safety by establishing a strict, no-delay go-around trigger if landing is not assured

When DA Applies

Approach Type	Uses DA?
ILS (CAT I/II/III)	✅ Yes
LPV (GPS Precision-like)	✅ Yes
LNAV/VNAV	✅ Yes
RNP AR	✅ Yes
VOR, NDB, LOC (non-precision)	❌ Use MDA instead

DA vs. MDA

Feature	Decision Altitude (DA)	Minimum Descent Altitude (MDA)
Approach type	Precision/APV	Non-precision
Action required	Immediate go-around at DA if no visual contact	May level off at MDA and wait until MAPt
Descent profile	Continuous descent	Step-down, level-off
Published as	Altitude or height (DA or DH)	Altitude (MDA)
Missed approach trigger	At altitude	At Missed Approach Point (MAPt)

Visual Reference Requirement

To continue below DA, the pilot must have:

✅ The runway environment in sight (lights, markings, threshold, etc.)
✅ A normal, stabilized approach path to land
✅ Sufficient visibility per approach minimums

Example on Approach Chart

DA(H): 1220 ft (200 ft)
DA = 1220 feet MSL
DH = 200 feet above threshold elevation
Decision must be made at 1220 ft based on instruments

Phraseology Examples

Situation	Phrase
Approach briefing	“Decision altitude one two two zero feet.”
At DA with no visual	“No contact, going around.”
At DA with runway in sight	“Runway in sight, landing.”