There is no standard definition of "due regard". However, the Chicago Convention Chapter One, General Principles and Application of the Convention, says that, "…States undertake, when issuing regulations for their state aircraft, that they will have due regard for the safety of navigation of civil aircraft"”.
Note: The International Civil Aviation Organisation (ICAO) Convention describes "state" aircraft as those aircraft used in military, customs, and police services.
Some operational situations do not lend themselves to International Civil Aviation Organisation (ICAO) standards and flight procedures. Typically these may be politically sensitive missions, military contingencies or classified missions. When operations of this type are not conducted according to ICAO standards and flight procedures, they are said to be conducted under the “due regard” prerogative for State Aircraft and the aircraft commander should operate the aircraft with “due regard” for the safety of all civil traffic.
Crews operating OAT with "due regard" may not be obliged to communicate with ATC and/or operate their SSR transponders. Consequently their intentions may be unknown to ATC and it may not be possible for the prescribed separation minima to be preserved in these circumstances. Any change to the flight path of the civil traffic could result in more dangerous situations arising because the OAT is operating “due regard” and expecting the civil aircraft to behave in a predictable manner
- Military aircraft often conduct exercises above ‘international’ waters. Although these operations can be notified to ATC authorities, because of the nature of the operations and the fact that the aircraft are operated with “due regard” it can be difficult, if not impossible, for ATC to achieve coordination.
- Maintaining only 500ft separation (“well clear”) is likely to be insufficient to prevent civil traffic from receiving Airborne Collision Avoidance System (ACAS) traffic advisories (TA) and resolution advisories (RA). (Note: This assumes that aircraft operating with "due regard" are also operating their SSR transponders.)
Some aerial activities may be so incompatible with the ability of state aircraft to apply "due regard" that State authorities may wish to consider the need for establishing airspace structures for exclusive use and in certain circumstances complete segregation.
Where such action is not possible, State aircraft operating authorities and pilots can take a number of measures to mitigate the impact of "due regard" operations on civil traffic:
- Prior coordination with national airspace/ATC authorities can limit potential communication problems.
- Aircraft commanders should also make themselves familiar with:
- the type(s) of civil aircraft operations;
- the airspace organization and responsible ATS unit(s);
- ATS routes and their dimensions; and
- relevant regulations and special rules, including airspace restrictions.
- A comment can be made in the remarks section of the flight plan, if one is filed.
- Include the point or fix where "due regard" will commence/end on the flight plan.
Before an aircraft commander declares "due regard" a number of conditions could be met, for instance:
- the aircraft could be operated in Visual Meteorological Conditions (VMC); or
- the aircraft could be operated within surveillance and radio communications of a surface or airborne (e.g. AWACS) radar facility; or
- the aircraft could be equipped with airborne radar that is sufficient to provide separation between themselves, aircraft they may be controlling, and other aircraft; or
- aircraft could be operated outside controlled airspace and, when possible, away from high density traffic areas.
- ICAO Doc 9554, “Manual Concerning Safety Measures Relating to Military Activities Potentially Hazardous to Civil Aircraft Operations”.
- ICAO Doc 9433, “Manual Concerning Interception of Civil Aircraft”.