Definition
The actual radio navigation signal radiated by a ground-based or satellite-based navigation aid, as received by an aircraft's onboard equipment. It refers to the usable navigation guidance present in the airspace itself, independent of how the aircraft processes or displays it.
Plain English
The navigation signal that is actually being broadcast and is available in the air for an aircraft to receive and use.
Context Anchor
Seen in instrument procedure discussions when the FAA is describing whether the transmitted navigation signal itself supports a procedure, such as a copter-only approach.
Derivation
A literal phrase. 'Signal' refers to the radio transmission carrying navigation information. 'In space' means in the airspace where aircraft fly — not outer space. The phrase emphasizes that the signal exists out in the operating environment, available to any properly equipped receiver.
Why Pilots Care
It determines whether the navigation signal is usable and reliable enough to support the published approach minimums.
Grounding Statement
Picture the helicopter flying through an area where the navigation signal is present in the air, ready for the aircraft’s equipment to receive and use.
Intuition Check
Do not read signal in space as a hand signal, cockpit indication, or something related to outer space. Here it means the navigation signal physically reaching the aircraft through the air.
Example Sentence 1
The approach was unavailable because the signal in space was flagged out of service by NOTAM.
Example Sentence 2
Terrain interference reduced the signal in space and raised the minimum descent altitude for the procedure.