Aeronautical Terms beginning with D

D/D

DME/DME

---

D/D/I

DME/DME/Inertial

---

DA

Decision Altitude

---

Decision Altitude (DA)

In an approach with vertical guidance, DA is a specified altitude expressed in feet above mean sea level at which a missed approach must be initiated if the required visual references to continue the approach have not been established.

---

DF

Direct to Fix

---

Discontinuity

A discontinuity is an interruption in the sequence of waypoints within the active onboard flight plan (primary flight plan loaded into FMS).

---

Distance Measuring Equipment

(DME) DME/DME (D/D) RNAV. Refers to navigation using DME ranging from at least two DME facilities to determine position.

---

DME

Distance Measuring Equipment

---

DME/DME/Inertial

(D/D/I) RNAV. Refers to navigation using DME ranging from at least two DME facilities to determine position along with use of inertial systems, inertial reference system (IRS) or Inertial Reference Unit (IRU), to provide sufficient position information during limited DME gaps.

---

DOD

Department of Defense

---

DP

Departure Procedure

---

DTK

Desired Track

---