Why do most vehicles seen at airports use slow flashing orange beacons?

Question

Most vehicles seen at airports use slow flashing orange beacons rather than a rotating beacon, is there a purpose to this? What is the correct name?

Answer 1

ICAO

Mobile obstacles at airports are lighted with type C obstacle lights, this refers to airport lighting practices defined in ICAO in Annex 14:

6.2.2.6 Low-intensity obstacle lights, Type C, displayed on vehicles associated with emergency or security shall be flashing-blue and those displayed on other vehicles shall be flashing-yellow.

Rotating vs. flashing

There is no difference in rotating vs. flashing. Flashing is used with modern technologies, e.g. LED, as the number of on/off cycles has little impact on lifetime, contrary to filaments which are subject to thermal fatigue when temperature changes.

Flashing frequency

From same ICAO document:

Table 6-1. Characteristics of obstacle lights
Low-intensity, Type C (mobile obstacle): Flashing (60-90 fpm)

This choice is likely based on physiological considerations, to limit ocular fatigue, and impact of a repeating signal on brain.

Color

Red/blue are for emergency/safety vehicles, orange for support vehicles.

^Source

FAA

FAA implements ICAO recommendations in AC 150/5210-5.

Airfield Service, Aircraft Support, and Airport Operations Vehicles
The standard for identification lighting is a yellow flashing light that is mounted on the uppermost part of the vehicle structure. A steady yellow light designates vehicles limited to non-movement areas. [...]

4. TLTVs. An LED light bar placed above the operator’s cab may be used in place of the rotating yellow flashing light. In addition, a yellow flashing light (of any type) must be installed on the upper left-rear and right-rear corners of the TLTV, and must be activated when an aircraft is in tow.

For color:

1. Airport Emergency Vehicles.
   a. Ambulances. Per the most current version of Federal Specification KKK-A-1822.
   b. ARFF Vehicles. Red or a combination of red-and-white flashing lights per the chromaticity requirements in Appendix B.

2. Airport Security Vehicles. Signal blue or a combination of red and signal blue flashing light per the chromaticity requirements in Appendix B.

3. Airfield Service, Aircraft Support, Airport Operations, and Other Vehicles. Yellow flashing light per the chromaticity requirements in Appendix B.

For frequency:

Lights must flash at 75 ± 15 flashes per minute