What are Apron Safety Lines?

Apron safety lines are continuous painted lines on an apron that mark where ground vehicles and servicing equipment must stay clear of aircraft.

An apron is where aircraft park, load and get service. The lines show vehicles and equipment where they may stand and drive. The day marking page covers the whole set of surface markings. This page covers the safety lines.

What the standards require

Colour

Neither ICAO nor EASA names a colour for apron safety lines. They set one test. The colour must be conspicuous and must contrast with the stand markings. The stand markings are yellow (Annex 14, 5.2.1.5). EASA GM1 adds that safety lines are narrower than the guidelines for aircraft, and of a different colour.

The standards leave the choice open, so check the apron plan of each airport.

The elements

• Wing tip clearance line. It marks the edge of the safety zone clear of the path of the critical aeroplane’s wing tip. EASA says to draw it at an appropriate distance outside the normal path of that wing tip.
• Service road boundary line. It marks the edge of the road that ground vehicles use.
• Equipment limit line. It marks the limit of the area where vehicles and equipment park when they are not in use. EASA says to keep ground equipment and vehicles outside the set limits when aircraft manoeuvre, or when the equipment stands unattended.
• Passenger path line. It shows passengers and escorts the route to walk on the apron, clear of hazards. EASA says a pair of lines with zebra hatching between them may be used.

Which side is safe

A line alone does not say which side is safe for equipment. EASA GM1 gives these methods:

• Spurs on one side of the line. The side with the spurs is safe for parking vehicles and equipment.
• A second line on one side. It is either a discontinuous line of the same colour or a continuous line of a different conspicuous colour.
• The words “Equipment Limit”, painted on the side that equipment uses. A driver reads them from that side.

Apron service road markings

EASA treats the road itself in CS ADR-DSN.L.597. The markings define the road limits, and they give safe separation from aircraft.

• The markings are white and at least 10 cm wide.
• The edges are continuous. The middle is continuous or broken.
• Where the road crosses a taxiway or stand taxilane, the edge marking is dashed across the crossing. The dashes are 1.0 m long.
• The markings stop when they meet other apron markings. The gap is at most 1 m on each side.

Perimeter service roads for security or maintenance are not apron service roads (GM1 ADR-DSN.L.597).

The FAA approach

The FAA does not set a standard for these lines. AC 150/5300-13B, paragraph 5.12, lists the apron markings that FAA standards cover. The list does not include safety envelopes. It names industry best practices for aircraft safety envelopes, passenger walk paths and equipment parking. It points to Airports Council International (Apron Markings and Signs) and Airlines for America (Recommended Apron Markings and Identifications).

AC 150/5340-1M gives one standard marking for a related job. It is the non-movement area boundary marking (5.4). It is two yellow lines, one solid and one dashed. The solid line lies on the non-movement side. Some airports without a control tower use it on aprons to separate vehicle and equipment traffic from the area where aircraft taxi. No part of a parked aircraft may overhang it. The FAA vehicle roadway markings are white (5.2).

The FAA also sets clearance for service roads. The lateral clearance from a parked aircraft to the road is at least 10 ft (3 m). It can fall to 6 ft (1.8 m) if the aircraft stays at least 5 ft (1.5 m) above the tallest vehicle (AC 150/5300-13B, 5.19.1).

Safety lines and stand clearances

A safety line shows a limit on the surface. A stand clearance is a distance rule. EASA CS ADR-DSN.E.365 and ICAO Annex 14, 3.13.7, recommend minimum clearances for an aircraft that enters or exits a stand. The clearance is to any adjacent building, aircraft on another stand or other object. They are 3 m for code letters A and B, 4.5 m for C and 7.5 m for D, E and F. The apron design sets where each line goes. The standards do not tie a safety line to one of these values.

Checking apron safety lines

A check of an apron looks at these items:

• Lines are continuous, at least 10 cm wide and clear of wear.
• The line colour contrasts with the yellow stand markings.
• Wing tip clearance lines match the aircraft that use the stand.
• Equipment limit lines show the safe side, by spurs, a second line or the words “Equipment Limit”.
• Service road markings are white, with 1.0 m dashes at taxiway and taxilane crossings.
• Lines match the current stand layout.

TarmacView’s runway surface scan captures georeferenced imagery of the pavement. A person reads the markings on that imagery. The service is in development and is not offered yet.