# Loiter (aeronautics)

In aeronautics and aviation, loiter is a phase of flight. The phase consists of cruising for a certain amount of time over a small region. The loiter phase occurs, for general aviation, generally at the end of the flight plan, normally when the plane is waiting for clearance to land.

In military flights, such as aerial reconnaissance or ground-attack aircraft, the loiter phase is time the aircraft has over a target. Cruise is the time period the aircraft travels to the target and returns after the loiter.

In astronautics, the loiter phase of spacecraft used for human spaceflight may be as long as six months, as is the case for Soyuz spacecraft which remain docked while expedition crewmembers reside aboard the International Space Station.

## Endurance

The endurance of the aircraft during the loiter phase is calculated using the following (Breguet formula):[1]

${\displaystyle E={\frac {1}{C}}{\frac {L}{D}}\ln \left({\frac {W_{i}}{W_{f}}}\right)}$

where:

• ${\displaystyle E\,\!}$  is the endurance (dimensions of Time)
• ${\displaystyle C\,\!}$  is the Specific Fuel Consumption (dimensions of 1/Time)
• ${\displaystyle L\,\!}$  is the total lift force on the aircraft
• ${\displaystyle D\,\!}$  is the total drag force on the aircraft
• ${\displaystyle W_{i}\,\!}$  is the weight of the aircraft at the start of the phase
• ${\displaystyle W_{f}\,\!}$  is the weight of the aircraft at the end of the phase