Month: August 2016

Issue

London Heathrow has a desire to ensure every last ATM is utilised however only wishes to add more flights if it does not impact on performance at the airport. Resilience is driving many operational changes to ensure that delays and passenger experience is not compromised. One method of improving resilience is the spreading of flights across the day.

ACL Concept

ACL has the expertise and the data to analyse an airport schedule and suggest constraints on the runway, the terminal, parking and gates to help the airport and the airlines deliver a service to the planned schedule.

ACL recently provided analysis on the London Heathrow Airport schedule to evaluate the impact of introducing a 5 minute scheduling constraint to improve the spread of flights across each hour of the day. This included determining the probable number of moves by arrival and departure to achieve a five minute runway constraint which could then be used to determine the likely reduction in delay. Previously Heathrow had been coordinated with a runway ten minute offset constraint for over 20 years.

ACL was the innovator of this project, we were able to incorporate other stakeholder contributions to deliver a feasible schedule that utilised the five minute rnway constraint.

Part of the delivery involved demonstrating feasibility and forecasting probable outcomes.  ACL also worked with the airport and NATS to demonstrate a reduced delay profile with the benefit of improved on time performance.

The work involved re-coordinating the historic baseline to the agreed new five minute constraint in advance of the SHL, this allowed airlines to accept or reject requested voluntary moves.

The final work involved Coordinating to the new constraint in summer 2016 and winter 2016/17.

Benefits

The new constraint produced an operationally deliverable schedule having removed infeasible periods of eight movements on arrival and eight departure movements in any given five minutes period.

The change has the potentially to reduce delays and stack holding with the added benefit of on time performance improvement for the airport infrastructure and the airlines schedules.

Process

All requested historic time moves by ACL within the five minute schedule were voluntary moves, Airlines had the right to refuse to move off their historic slot time due to their own commercial and connection requirements. The voluntary situation acknowledged that not all five minute overages would be eliminated in the first season using the new constraint. ACL worked closely with airlines to encourage acceptance of the suggested moves to ensure maximum impact.

Outcome

ACL eliminated eight movements in five minutes in one season, with the majority of five minute periods below the five movement level. There are a few minor periods of five minutes where six movements are scheduled. It is expected that over the next three equivalent seasons the overages will be reduced to the five movement per five minutes declared capacity.

The initiative will enable NATS/ Airport operations/ Airline operations/handling agents to have improved ability to deliver to the schedule plan.

Background

London Luton experienced continual growth over a number of seasons, culminating in a significant breach of the declared terminal departure limit on particular days throughout the Winter 2011/12 season. Under the Level 2 process, ACL requested carriers to make voluntary moves to smooth the peaks across the affected period.  This process could not be enforced and resulted in carriers refusing to move.  The peak continued to grow, increasing security delays on departures and the airport began to explore the possibility of changing the status of the airport from Level 2 to 3. Fig 1 is an indication of the overages caused by airlines refusing to accept voluntary adjustments in Winter 2011/12

Fig 1: Terminal departure throughput by day of week 0630-0845 (GMT) Winter 2011/12

Process

The airport commissioned an independent capacity review whilst ACL advised on the process and timelines behind moving an airport from Level 2 to Level 3, highlighting the deadlines required to meet the Worldwide Scheduling Guideline date for declaring the change.   ACL analysed the data which demonstrated growth over the seasons along with the number of refused moves which were impacting the declared capacity.   The airport and ACL jointly held individual meetings with the carriers and general aviation handling agents to explain the issues and the reason for the request to change the status from Level 2 to 3.

The capacity review identified parking and taxiways leading to the runway along with departing passenger throughput in the terminal as areas for concern going forward, all contributing to delays in the morning peak operation.  ACL were already modelling parking in the score system to ensure schedule feasibility against the number of available stands but again if this parameter were to be breached ACL could only request and not enforce a schedule adjustment under Level 2.

The UK Department for Transport (DfT) were engaged and ACL contributed an independent voice to the debate on the background to the change of status request by the airport.  ACL remained in close contact with the DfT to ensure any questions were answered impartially.

The DfT put this information out for consultation and carriers were invited to respond with their views.  Fourteen entities responded with one against the change in status. The Secretary of State concluded the shortfall of capacity was of such a serious nature that significant delays could not be avoided at the airport and there were no possibilities of resolving these problems in the short term.

London Luton Airport was formally declared as Level 3 effective Summer 2013.

Benefits

Level 3 status allowed ACL to enforce slot adjustments and apply a higher level of control over the schedule from Summer 13 onwards.  This resulted in the schedule being smoothed out across the 0630-0845 time period instead of the bunching previously experienced.

Fig 2: Terminal departure throughput by day of week 0630-0845 (GMT) Winter 2016/17

Value

ACL will work with airport customers to impartially gather the data to present to interested parties. With detailed regulatory knowledge of both the EU Slot Regulation and the Worldwide Scheduling Guidelines, ACL is able to offer guidance on the process behind a change in airport status.  With close interaction between ACL and all stakeholders the message is conveyed to ensure all parties understand the implications and reasons for the change.

Outcome

The role of ACL is to maximise capacity at airports.  Where demand exceeds capacity, further controls are required to smooth the schedule and remove sharp peaks which may impact the airports ability to deliver a punctual schedule.  Level 3 allows for the control of slot allocation along with the monitoring of slot usage to ensure carriers adhere to the cleared slot.

ACL will also offer advice to airlines and the relevant authorities on all matters likely to improve airport capacity or slot allocation flexibility, in particular on any area which will help the airport return to Level 2 or Level 1.