Application of legal case to ACAS XA

Background in ACAS X

• Worked on TCAS II for 28 years– SARPs for ACAS II

• Chairman of EUROCAE WG-75• Currently under contract to the FAA– developing ACAS XA and ACAS XU

User Group Experience

• Joined at quite a late stage• Fascinating but not reassuring– Undermined my confidence in legal process– No longer trust it to reach sensible decisions

Results from test application• For whom? Methodology or ACAS X?• w.r.t. methodology, it demonstrated that

the process can indeed be applied to ACAS – Determines the exposure of each actor to the

risk of being found liable for an accident– but it does not evaluate the probability of the

accident, nor of the case being brought– nor does it seek to determine who is liable

Use in Concept of Operations

• Already reported: ACAS XA =TCAS II• There no possibility of use in ACAS X ConOps• But that would be the best place to use

anything that can be used

Use in design of ACAS XA

• I agree it is essential to define procedures– Saying procedures must be defined does not help• We know it• Deep prejudice in favour of providing information • There are other systems that just show tracks

– Track and TA will aid visual acquisition• In the USA pilots are expected to rely on visual evidence,

in Europe EASA warns against that

Use in design of ACAS XA

• So – give them an RA– Again, I happen to agree– Not going to happen because endangers timescale– Significant work involved– Comments about maturity and encryption misplaced• The technology is mature • We want ADS-B to be open – that is the point of it• Design of ADS-B not under control of ACAS X team

Final comments• The application of well-meaning disciplines is

not always beneficial– “The road to Hell is paved with good intentions”

• Already required to be safe and effective• The only use I can see for the Legal Case is to

help transfer the risk between actors– to avoid litigation by ensuring that those against

whom there is a credible case cannot pay