Timing in aviation is everything

Time or Timing?

Well, both really.

Pilots’ decision making models, regardless of which acronym is used, generally all consider ‘Time’ as the first and most critical thing to establish. If you don’t have time to get to the ultimate runway then it doesn’t matter that it is 1000m longer and has a higher RFF category than the one nearer you. If you don’t start the timer in an emergency power level event, you might lose track of what your battery has left…

So of course, both ATCOs and pilots, along with other safety critical roles in aviation, always have time on their mind – how to manage it, ‘make’ it, prioritise actions when it is limited, endure hours of it at 3am when fatigued…

But while time itself is a critical resource in aviation, what we want to think about today (by means of some examples) is timing, because get this wrong and you might find you’ve run out of time too.

Planning Timing

Planning the timing of certain actions is a key part of timing management. We want to look at the planning of actions which can have a significant impact on this – the “threat and error management of timing” you might say.

Workload management and the planning of actions and briefings is important at all times to help improve capacity, resilience to change, and ensure good threat and error management is always key.

• Briefings: Consider the best timing to do these to ensure crew are able to listen and take it in, as well as ensuring awareness for ‘dynamic’ situations such as taxi routes
• Checklists and non-normals: Again, a consideration of the best time to do this is important. Asking “what is the most critical thing right now?” is a useful well to help prioritise. Carrying out a stuck engine-ice valve while in a busy CTZ is probably not the best timing
• Communications: Whether it is to the crew member in the flightdeck, across the radio, to cabin crew or passengers, a large part of effective communication is getting the timing right to ensure messages can be received and comprehended.
  • Weather avoidance calls is an area that ATCOs and pilots often say it is hard to get right. Too early may be inefficient for crew, too late and ATC may be unable to assist if other traffic is a conflict

Managing timing, particularly on approach, is something ATCOs and pilots should be very familiar with. Wake turbulence is generally calculated based on time or distance, and poorly timed actions can impact separation significantly. On the ground or, more specifically, when thinking about the runway, the timing of certain actions by both ATC and pilots can impact the risk of runway incursions.

Time, and good timing, are both important

WAKE SEPARATION

• Speed: Pilot management of speed is key to maintaining separation, and when directed by ATC, they should ensure they reduce/maintain speed expeditiously and effectively. This requires planning and consideration of potential threats which might change the ‘expected’ performance for that specific flight:
  • Aircraft performance (ie weight) and environmental conditions (ie tailwinds) can impact the ‘time it takes’ to slow down and configure
• Runway Occupancy: ATC plan separation based on expect time for aircraft to remain on the runway. Not every event can be planned for, but if crew know, for example, that they will be unable to make an expected exit, informing ATC early will help them ‘time’ the sequence to account for this.

In 2023, a Lufthansa A350 diverted from KSFO/San Francisco to KOAK/Oakland after calculating they had insufficient fuel to continue holding indefinitely for San Fran. A thumbs up for their time management, but what led to this was also a ‘timing’ related issue.

The A350 had had a lengthy departure delay and had arrived at San Fran hours later than their usual arrival time, and it was evening already. Their operator had an SOP in place prohibiting crew from accepting visual approaches at night. The visual approach is a convenient method used by ATC to improve runway efficiency by passing separation responsibility to pilots.

When cleared for a visual approach, the crew advised they were unable. However, at this point, ATC were unable to find a way to fit the aircraft into the flow. Several ‘timing’ related factors contributed to this: ATC being unable to manage wake separation and flow, the crew’s timing for advising ATC and of course, time available with fuel.

One factor which played an important part in the above example was the timing of sharing information between ATC and crew. Consideration as to the best time to alert ATC of differences, limitations or requirements in order to support ATC in managing their “bigger” airspace picture is important, as if ATC ensuring there is space (time) available for crew to share that information when they need to.

In 2024, a B787 operating onto runway 31R at JFK was asked by ATC, during their landing roll, which exit (V or U3) they planned on taking. The crew responded with U3 (the further exit) and ATC replied that they needed to expedite due traffic behind on the approach. The crew then responded with an explanation that they were heavy and unable on that day to make the earlier exit. ATC told them the information was unnecessary and that they just needed to expedite.

At what point (if at all) the crew should have alerted ATC to a ‘difference on the day’ (they were not going to take the dual exit) is one question. The other is the timing of ATC’s call to the crew and whether the ‘shared mental model’ of the overall operational picture could have been shared much earlier to avoid assumptions and misconceptions.

RUNWAY INCURSIONS

Anytime an aircraft receives, or ATC gives, a critical clearance consideration of the risks of ‘bad timing’ should be on their mind! What do we mean by this?

• Frequency changes: How does this potentially reduce situational awareness?
  • Changes to a frequency when vacating an active runway parallel to a second active runway may reduce capacity and SA
  • Different controlling frequency to active runway frequency providing clearance to cross may reduce SA and increase risk of errors
• Distractions: Calls from ATC to pilots on short finals or during the landing roll regarding exits and taxi clearances may cause distraction resulting in missed exit, aircraft remaining on runway etc

The RJTT/Tokyo crash involving an A350 and a lifeguard rescue aircraft in 2024 occurred, in part, due to ‘bad timing’ regards change of frequencies and clearances. The life guard aircraft was not on tower frequency when the A350 was cleared to land.

A JFK controller cleared 4 aircraft to cross an active runway after an aircraft had been cleared by a different controller (tower controller for the active runway) for take-off leading to a multi-aircraft runway incursion and a rejected take-off.

In both examples, the factor highlighted was a single factor in a chain of contributing errors and threats, But each highlights the critical nature of timing when it comes to clearances which involve takeoff clearance, landing clearance, line up or runway crossing clearances. All crew and ATC should consider the timing of when a clearance is received of given, and should confirm that it makes sense in context of the operation. Always consider the possibility of a mistake and stay alert and aware.

Reduction in safety, efficiency or effectiveness are often a case of bad timing

Intervention

Timing in intervention is critical. Intervene too late, or inappropriately for the time available, and it will not be effective. Pilots often use a version of ‘Ask, Suggest, Direct, Takeover’ which considers both the importance of intervening (is it lapse, a slip, an intentional disregarding of a safety critical directive etc) and the time available (lots, not a lot, absolutely none…)

But intervention is also about the timing of the information being conveyed. ATC utilise a method – ASSIST – and the final line of this related to Time: Give the pilots time to collect their thoughts. Don’t harass them for information.

Intervention does not just refer to actions taken between pilots. Crew may be required to ‘intervene’ with ATC, other traffic, and of course ATC can intervene with crew. When it is appropriate to intervene, and particularly thinking about when to offer up information can make a huge difference as to how it is received, and understood.

Here are some examples to get you considering the different times an intervention might be required:

• Advising ATC that you are unable to fly a visual approach
  • Offering this information early so they can manage the flow
• Advising crew of a change to taxi clearance or exit
  • Advising crew to take a different exit while they are on short finals may be a distraction
• Intervening on the radio when you hear a wrong readback and ATC have not realised
  • Depending on whether it is leading to something urgent and critical such as a runway incursion will impact how to intervene

But as we said, intervention is as much about the timing of the intervention, so here are some examples of when the timing has played a major part in the effectiveness of the outcome.

WRONG TIME

There had been numerous distractions on the ground, so we were completing certain things out of order – like the briefing. Partway through the briefing and we received the clearance. The Captain abruptly stopped the briefing, accepted the clearance without me having time to review it, and then said to continue briefing as the clearance was what we expected.

I was unsure, but thought the clearance had contained a different SID transition and so mentioned this to the Captain, but he dismissed my concern saying it was as expected. After we had finished briefing I suggested we check the FMC against the chart but the load sheet came through distracting the Captain again. I therefore decided to check the FMC and load the right SID transition myself.

While loading the correct transition, the Captain stopped me – he had seen me doing something and was out of the loop so was concerned about what I was doing. As he had already shown he was at capacity managing distractions, and my previous interventions had not been well received, I decided to stop and wait for him to have the time to really pay attention. When he did, I said again “I think we have the wrong transition loaded, do you mind if we go through the chart and the FMC together to check?” This time, he received the info and we were able to correct it as required.

TIME CRITICAL

In 2020, a B787 was on approach into LFPG/Paris Charles de Gaulle, runway 09L. On contacting tower, they are given a clearance for a sidestep approach to the parallel runway 09R. The crew question it but do not get an adequate clarification from tower and they fail to ‘intervene’ further with ATC by requesting more clarification (which would have shown it was given in error).

The B787 continued, but a A320 on the ground realised the error – they had been cleared to line up runway 09R and as they turned onto the centreline, they visually say the Boeing 787 turning to aim for the runway. They questioned it with ATC but with the aircraft at approximately 0.7nm, the A320 crew directed the B787 to go around, intervening by effectively “taking over” from ATC.

OUT OF TIME

United Airline flight 173 crashed in 1978 after a failure with the gear resulted in the crew troubleshooting for over an hour leading to fuel starvation, engine flameout and the crash. The flight engineer attempted to inform the crew twice about the reducing fuel reserves but did not intervene appropriately.

The Captain lost track of time, distracted by the gear issue and failed to consider time or to prioritise actions. Other factors like cockpit gradient, human factors etc also played a major part in this, but the timing of intervention and time management were two critical factors.

Just some examples…

These are just a few examples of situations where timing is a critical factor in efficiency, effectiveness and potentially safety within aviation operations. Whether it is the consideration of the best timing to share information, potential environmental and performance factors which might impact expected timings, or thought given to how bad timing might reduce situational awareness, timing is an often overlooked but important factor to think about.