The background to these types of situations and some good advice is given in the paper
‘PACE’.
The scenarios posed are never that clear cut, situations are dynamic and depend on perception, and thus it is necessary to consider how they arose.
Having a good SOP is essential. It provides the ‘rule’ – the boundary of safe operation, and a common base for crew awareness and call out. Thus if the aircraft is at a limit, then both pilots should know what to call and what action is required. A failure to act might be due to lack of awareness by the pilot flying (PF) – then the non flying pilot (NFP/MP) should make a call. Alternatively, the PF could be deliberately breaking the rule, in which case s/he should provide an explanation at the time and/or the NFP provide an alert/seek explanation.
A major factor in these situations is timing. When considering an aircraft 20 kts fast at 500ft, then the limit boundary (SOP) can be anticipated. At best, the aircraft could be expected decelerate at 2 kts/sec (20kts in 10 sec – EFIS speed trend) – any faster might be deemed windshear or be very destabilizing to the flight path. Thus with a descent rate of 10 ft/sec (600ft/min) a deceleration should commence at least 100ft above the limit altitude. A more practical situation is with a lower deceleration starting 200ft above, i.e. 700ft.
At this altitude a helpful speed awareness call could be made – ‘Skipper we require 145 kts at 500’. Note the informality (PACE) and the provision of a speed value, the latter helps the PF’s awareness and reduces mental workload in reconsidering what value equates to Vref+20 or what is the SOP etc. The principle here is for every call that may create a ‘problem’ (action required) then provide a solution or guidance to aid the required awareness / action – but don’t tell the Captain what to do.
If the message requires reinforcement, then provide a statement of ‘because’, i.e. ‘don’t forget that this is a short / wet runway’, or ‘we are at max landing weight’.
There are skills associated with verbal intervention; e.g. situation awareness and the ‘PACE’ of communication. A first officer must continuously improve these skills and experience through learning (observation and remembering situations / visualizations) such as the aircraft’s deceleration capability, and how this varies with weight, head wind (always remember numbers). Practice building a mental model of all of the factors in an approach and landing, and an awareness of how close to the boundary an operation can be and/or the rate of deviation; see
ALAR for background information. Debrief yourself after every flight – what did you learn, why; what was not known – then find out.
If SOPs have been exceeded and no explanation given at the time (or an unsatisfactory explanation) then it is essential that the situation and decision making involved be debriefed. Ask the Captain for the reasoning behind his decision, what were the factors he considered and why. If these differ significantly from your perception of the situation (and SOPs) then asking him to discuss these issues.
If the outcome is unsatisfactory then avoid confrontation. If company procedures require a report then fill it in, there is always the option of confidential reporting, both internally and externally. Always consider that you may have misunderstood the situation / explanation. Thus seek the advice of another Captain before acting, but don’t write the event off as your mistake – more often than not it is the situation or the SOP that creates the opportunity for error, and these must be reported.