Improving Block Times: Key To Reducing Aviation Delays

Timing Is Everything

Just like in any race, the timing of when the clock starts and stops separates winners from losers, and its impact on the results becomes more significant as the distance of the race decreases. Milliseconds separate 1st, 2nd, and 3rd place winners in a 100-meter sprint whereas minutes often separate 1st, 2nd, and 3rd finishers at a full marathon. 

In commercial aviation, departing and arriving on time has much in common to a race in that every turnaround activity has well defined start and end times and there’s little tolerance for error; running on-time is crucial for the system to operate efficiently and dependably. In addition, time is tremendously valuable and every minute that an aircraft is operating is precious not only because of the cost of fuel burned but also the costs associated with crew time, aircraft time, (including engines and APUs), the costs of occupying a busy gate or a busy taxiway at an airport, the value that every passenger assigns to their time (multiplied by how many passengers are on-board), etc… 

On-time performance is also crucial to an airline’s reputation and reporting it accurately is a requirement demanded by the FAA. Commercial carriers in the USA must report official operational information every month. 

Arriving “On-Time” 

To improve the chances of reporting better on-time performance, airlines have been consistently adding time to their published flight schedules in a practice that some call schedule padding. You may notice that flights these days seem longer on paper but in reality, they last just a bit longer than a decade ago and the common PA announcement from the pilot “folks good news, we got you here early, bad news our gate is still occupied….” is way too common these days.

While adding a buffer to a flight segment (block time) makes sense to accommodate for common operational challenges, random weather conditions, and ATC routing, adding too much buffer is incredibly inefficient, for the airline, the airports, the passengers, and the ground service providers. Everybody plans around published schedules and advertising a 2-hour flight as 2:40hrs is not doing favors to anyone. 

Clock Start/Stop

Carriers use automated and/or manual systems for collecting flight data, and official flight departure and arrival (block time) are key measurements. Those using an automated system rely on the Aircraft Communication Addressing and Reporting System (ACARS) or the Visual Docking Guidance System (VDGS) to report block time. To make it simpler, either a pilot-driven action starts the clock (ACARS) or an automated system (VDGS) can detect the start of the push after the aircraft has moved a few feet (depending on VDGS model). Based on the latest information available to the DOT, of the 15 reporting air carriers in the USA, 12 carriers (Alaska, Allegiant, Delta, Endeavor, Envoy, JetBlue, Republic, Hawaiian, SkyWest, Spirit, Southwest, and United) use ACARS (human driven), one carrier (American) uses a combination of ACARS, DGS and AFIS (automated), and two carriers (Frontier and PSA) use a combination of ACARS and a manual system.

How Block Time is Calculated 

 The FAA defines block time as the time interval that begins when an aircraft first moves from the departure gate or parking position under its own power (or by towing for pushback) and ends when 

it stops at the arrival gate or parking position after the flight. This period encompasses all phases of the flight, including taxi-out, takeoff, flight, landing, and taxi-in.

Because weather, Air Traffic Control (ATC) routings, and TSA checkpoints are beyond the airline’s control, the focus to calculate the proper buffer for block time lies on studying the “Air Carrier Delay” and Late Arriving Aircraft delay categories. The chart below shows the latest “Air Carrier Delays Causes” published by the DOT under the Air Travel Consumer Report (August 2024). Approximately 16% of total delays are controllable by the carrier in one way or another. 

Air Carrier Delay: The cause of the delay was due to circumstances within the airline’s control (e.g. maintenance or crew problems, etc.) 

Late Arriving Aircraft Delay: Previous flight with same aircraft arrived late which caused the present flight to depart late. 

Effective Actions To Optimize Block Time. 

Because “air carrier delay” and “late arriving equipment delay” categories are mostly attributable to the carrier (when late arrivals are driven by controllable causes) the areas of opportunity are: 

• Reduce taxi-in and taxi-out times: Breakdown taxiway circulation from apron movement and from gate approach/departure. Remove manageable outliers (long taxi-in/out events) from averages and understand how your airline’s methodology of starting and stopping the clock could be a factor that inflates taxi times artificially. 
• Eliminate friction while approaching or departing the gate: gate and team readiness are a factor in driving gate-holds (aircraft waiting short of the gate), delays for push-back and others which are baked into average taxi-times. 

The Federal Aviation Administration (FAA) defines taxi-in as the phase of aircraft movement that begins when the aircraft exits the runway after landing and ends when it reaches its designated parking position (gate/stand) and defines taxi-out as the phase that begins when the aircraft starts moving under its own power (or is pushed back by a truck) from the departure gate and ends when the aircraft reaches the active runway in preparation for takeoff. 

Because “taxiing” also includes gate arrival and departure, truly understanding what happens on the apron and at the gate (which are often airline controlled) will uncover a world of opportunities for improvement. 

Long taxi-in or taxi-out events often represent a systemic inefficiency in airport operations or can reveal a capacity limit, but airlines and ground service providers play an important role which can help to uncover what’s truly behind these events. Failure to correctly diagnose the root cause of the problem often results in drawing the wrong conclusions resulting in wasted investments, general frustration from working to solving the wrong problem or what is worse, limiting airport capacity. 

Management guru Peter Drucker once said that “what gets measured gets managed” so segregating taxiway circulation from apron movement from gate approach seems like a major opportunity to managing taxi times. At the gate, the impact of the methodology of starting and stopping the clock for taxi-times can reveal a world of issues like aircraft ready to push (break released) for several minutes but sitting idle, aircraft arriving but holding short of the gate for several minutes because of crew readiness, etc… because most pilots switch off the aircraft’s ADS-B transmitter while entering the apron, there’s not an accurate way to determine the true cause of long taxi events unless these occur purely on the taxiway while being monitored by surface surveillance or radar tracking technologies. 

Truly understanding the components of taxi times can greatly influence the calculation of block-times. The impact of schedule padding is far greater in short-haul flights which make up more than 67% of all commercial aviation operations in the USA, so every minute counts. 

Working To Solve the Right Problem – Synaptic Aviation

Multiple studies ranging from the FAA to individual commercial carriers often report taxi-in and taxi-out times at busy hubs averaging 7–15 minutes, with long events (>20 minutes) linked to factors like traffic peaks, arriving/departing runway configuration, and adverse weather conditions, including the need to de-ice. To address the long taxi problem, most airports opt for solutions in the form of new construction such as additional taxiways, new intersections, rapid runway exit taxiways, new de-icing pads, etc. 

AI and computer vision technologies tracking apron activities have reached a mature state over the last four years and when deployed, airport and airlines are quickly uncovering what percentage of long-taxi events have a root-cause right in the proximity of the gate/stand (last 100 yards) where you don’t suspect it. Since the system can automatically track ground service activity progress, and aircraft motion, it is incredibly accurate at calculating and predicting in-block and off-block times.

Reach out to us at info@synapticaviation.com to learn more about how this technology can transform the ways in which you run ground operations.