3rd ALIAS Conference Presentation 2015

2. Legal issues in
collision avoidance
systems
Elmar M. Giemulla
Berlin University of Technology

3. Legal Responsibility
• For an act:
The allocation of a field of activity to a person = Responsibility
to act
or
• For the consequences:
Who is liable for damages arising from the faulty exercise of the
responsibility to act? = Responsibility for the result
• Should liability be linked to the
- illegality of the act (responsibility of a human being) or
- illegality of the result (responsibility of a system)?
Which means: Liability just for the violation of a personal legal
right or only if someone has acted illegally?

4. Pilot in Command - Legal
Aviation law allocates responsibility to a human being
Chicago Annex 2 – Rules of the Air
• Chapter 1 – Definitions: Pilot-in-command.
The pilot designated by the operator, or in the case of general aviation, the owner, as being in command and
charged with the safe conduct of a flight.
• 2.3.1 Responsibility of pilot-in-command
The pilot-in-command of an aircraft shall, whether manipulating the controls or not, be responsible for the
operation of the aircraft in accordance with the rules of the air, except that the pilot-in-command may depart from these
rules in circumstances that render such departure absolutely necessary in the interests of safety.
• 2.4 Authority of pilot-in-command of an aircraft
The pilot-in-command of an aircraft shall have final authority as to the disposition of the aircraft while in
command.
• Chapter 1 – Definitions: Air traffic control clearance.
Authorization for an aircraft to proceed under conditions specified by an air traffic control unit.

5. PiC – ATC – TCAS?
Chicago Annex 11 – Air Traffic Services
• 3.3 Operation of air traffic control service
3.3.1 In order to provide air traffic control service, an air traffic control unit shall:
c) issue clearances and information for the purpose of preventing collision between aircraft under its
control and of expediting and maintaining an orderly flow of traffic;
• Problem: Contradicting TCAS advisories: The Lake Constance Midair Collision of 1 July 2002
– Facts: Two planes on collision course (BAL und DHL)
– Decision base:
• TCAS to BAL and DHL: Traffic Advisory (TA): “Traffic, Traffic”.
• ATC to BAL: Instruction: “Descend!”
• TCAS to DHL: Resolution Advisory (RA): “Descend, descend!”
• TCAS to BAL: Resolution Advisory: “Climb, climb!”
• ATC to BAL: Instruction: “Expedite descend!!”

6. Problem: Contradicting decisions
• Exercise of “Authority”= Decision as a result of a thinking process – Privilege
of human beings
• Conflicting decisions of human beings (PiC / Controller):
• Decision of PiC /command authority
• Decision of Controller (state authority)
• Unique privilege of PiC: “final authority”
Which means: Unrestricted priority of PiC
• Conflicting “decisions of men” / machine (Controller / TCAS)
• Can there be a conflict at all?
• Decisions of PiC and Controller/ ??? of TCAS
• “Information” oder “Advisory” are not “decisions”. They just support humans when
making a decision (TCAS = “additional set of eyes in the cockpit”)

7. All in all: The current legal situation
– Decisions are made by Man – not by the Computer
– Decisions are made by Man – possibly even in contrast to the computer
– Man decides which measures to be taken – not the Computer
– Man takes the necessary measures – not the Computer
However: Is this still realistic?
- Is the role of the Pic still that “archaic”?
- Hasn't “colleague Computer” actually already taken over?
- Or at least: Isn´t he on his way to do so?

8. Contradiction of “decisions” of the Controller
and TCAS-RA:
How shall the PiC “decide” when exercising his “final authority”?
• Obligatory according to ATC-Instruction?
In line with Annex 11 but can create a danger.
• Obligatory according to the TCAS-RA?
Relation “Man – Machine” would be turned around. Entrance into a new
“Philosophy”?
• According to his own assessment?
In line with Annex 2: “final authority”.
• In other words: Does the pilot still have the “responsibility to act”?

9. Official Reactions
• ICAO: “State Letter” 2002
“To ensure that national aviation documentation and that of aircraft operators highlight the critical importance of
following a TCAS-RA and not manoeuvring opposite to the sense of an RA, even if ATC issues conflicting
instructions”.
• EUROCONTROL - ACAS Guide 2014 / Excerpts
– Pilots are required to comply with all RAs, even if the RAs are contrary to ATC clearances or instructions
unless doing so would endanger the aircraft. Complying with the RA, however, will in many instances cause
an aircraft to deviate from its ATC clearance. In this case, the controller is no longer responsible for
separation of the aircraft involved in the RA.
– If an ATC clearance or instruction contradictory to the TCAS RA is received, the pilot must follow the RA and
inform ATC …
– Pilots sometimes do not follow an RA as they believe they have the threat aircraft in sight and judge there
will be sufficient separation.
– In this respect, ICAO provisions … are quite clear that in the event of an RA, the pilot must respond
immediately by following the RA unless doing so would jeopardise the safety of the aircraft.

10. Consequences
• Does that mean: “Rex non potest peccare” or “The king
can do no wrong”?
• “Responsibility to act” without any consequences?
– What are the criteria for a judge to attribute fault?
– Only intent and gross negligence?
– Can the PiC be held liable at all?
– Contradiction between his final authority (to know right from
wrong) and the later decision by a judge that the PiC has acted
wrongly

11. The current Liability Scheme
Montreal Convention:
• Article 17 para. 1:
– The carrier is liable for damage sustained in case of death or bodily injury of a passenger upon condition
only that the accident which caused the death or injury took place on board the aircraft or in the course of
any of the operations of embarking or disembarking.
• This is No-fault liability:
– Liability is not based on the “illegality of an act” (no responsibility of a human being)
– But is based on the “illegality of the result” (responsibility of a system)
• However: Exoneration is possible – referring to missing “illegality of an act”
Article 21 para. 2:
– The carrier shall not be liable for damages arising under paragraph 1 of Article 17 to the extent that they
exceed for each passenger 100,000 Special Drawing Rights if the carrier proves that:
(a) such damage was not due to the negligence or other wrongful act or omission of the carrier or its
servants or agents; or
(b) such damage was solely due to the negligence or other wrongful act or omission of a third
party.
Third Party Liability:
National legislation: Usually No-fault liability. Consequence of the Operation - liable is the operator

12. Is that realistic?
• Problems:
– What if PiC has no time to analyse and to establish an own judgement?
– What if he has no choice but to rely completely on TCAS?
– What if TCAS fails?
• Possible solutions:
– No gross negligence of the PiC
– Exoneration of the Carrier under Article 21 MC
– Liability of the Designer/Manufacturer