Christmas tree (aviation)

Oftentimes, bombers or tanker aircraft were stationed next to a readiness crew building (RCB), also known as 'mole hole' facilities.

To fix this, aircraft were repositioned on specifically designed alert aprons arranged in herringbone configurations, which then allowed the airplanes to pull out onto the runway as quickly as possible.

[1] This meant that the aircraft would be positioned at 45 degrees in relation to an alert apron center-line, leading to a short taxiway and then onto the nearest runway(s).

[3] The success of this formation also led to the adoption of the setup for the Boeing KC-97 Stratofreighter and KB-50 Superfortress aerial refueling aircraft.

This latter option was particularly critical for crews of the last three aircraft on the ramp that were located several hundred yards from the alert facility.

Diagram of 'Christmas tree' alert apron at Glasgow AFB , MT , c. 1957-1976. The yellow building in the lower right is a mole hole , also known as a readiness crew building.
Minot AFB , ND , in 1973 with its 'Christmas tree' at capacity.
In this Department of the Air Force site master plan for Wurtsmith Air Force Base from October 1957, the top box highlight the Christmas tree for bombers on ready alert, while the bottom box is the stubbed apron where aerial refueling tankers were kept.