Carroll McCormick reports on the optimisation of Southwest Airlines’ baggage handling system at Baltimore/Washington International Thurgood Marshall Airport.
After Southwest Airlines (SWA) acquired AirTran in 2011, the airline’s checked baggage inspection system (CBIS) at Baltimore/Washington International Airport operation went from taxed to overloaded. “Our flights peak at 199 per day and AirTran was running 48 flights per day. Our CBIS could not by itself handle the combined baggage for the two carriers,” recalls Jimmy Dickerson, Manager, Federal Airport Security Technology, SWA.
Beginning in May 2011, Arlington, Texas-based design/build firm Vic Thompson Company (VTC) led a team through a three-phase, one-year assignment that doubled the throughput of the CBIS, upgraded the computer control systems and completely renovated the Transportation Security Administration’s (TSA) checked baggage reconciliation area (CBRA). It achieved all this during SWA operations and without changing the CBIS’ configuration.
The project marks the first airport in a TSA programme to upgrade CBRAs to current standards at targeted airports. “This will allow for better ergonomics and better bag flow through the updated [screening] process and [using] current technologies,” explains Terry Spradin, TSA Regional Deployment Manager for electronic baggage screening programmes, responsible for 64 cities in the north east region.
Normally, given the luxury of time, VTC would have upgraded the sortation allocation controller before making changes to the CBIS programme. To meet SWA’s requirement that the CBIS throughput be vastly improved by the Thanksgiving holiday, however, VTC had to leave the computer upgrade until last. Here is how they did it:
The CBIS in Terminal A/B, out of which SWA operates, was commissioned in 2005 and could process about 1,200 bags per hour. It has six explosives detection system (EDS) machines. The CBIS is divided into two, three-EDS pods that can be operated independent of each other.
In preparation for Phases 1 and 2, during which the west pod, and then the east pod would be shut down and optimised, SWA built a 20x30ft (6.09×9.1m) drop-and-go baggage area to take up the slack. They positioned it in the lobby near an abandoned ticket counter and TSA equipped it with three Reveal Imaging Technologies CT-80 EDS machines.
While one pod was shut down TSA processed checked bags in the drop-and-go area, then put them on the ticket counter belt that took them to a baggage make-up area, where they were placed on carts and transported to SWA aircraft. “The drop-and-go solution demonstrated the willingness of the partnership with TSA and the airport. The local TSA had to retrain their folks to be recertified on the temporary machines. This is not an easy thing to do,” Mr Dickerson emphasised.
Phoenix-based G&S Mechanical USA replaced 118 conveyor drive motor/reducer packages with variable frequency drive (VFD) motors manufactured by SEW Eurodrive. VFD motors can be easily adjusted to different speeds, and herein lay a clever strategy: “We replaced the drive packages and left the conveyors running at the original belt speeds,” explained G&S Owner and President Jim Goertz. Later, after replacing the other electrical and mechanical equipment required for the optimisation, G&S adjusted the VFD motors to increase the belt speeds.
In Phases 1 and 2, Louisville, Kentucky-based controls engineering company Alliant Technologies worked on the control system, while G&S replaced electrical equipment. G&S also supplied and installed 12 of its queue conveyors and a section of G&S general transport conveyor, which are better at centering bags on the belts and require less maintenance than the old conveyors. G&S also replaced seven Siemens HSD I diverters with new Siemens HSD II units.
The latter are able to divert baggage without causing them to turn and lose orientation. This is critical to the proper functioning of the sensitive baggage tracking system. If, say, a 28x18in (71x45cm) bag turns, the spacing between it and the bag ahead of it changes and the length of the bag may be seen to change, which may make the system lose track of the bag. Lost bags go to CBRA for manual screening, a frequent occurrence that was overwhelming TSA staff and shutting down the old CBIS.
Terminal A/B was not designed to accommodate a CBIS. It was shoehorned into a space too small for forklifts, so G&S had to disassemble the existing diverters and queue conveyors and take them out in pieces, along with the old electrical conduits. Then G&S brought in the new equipment and assembled it in place in reverse order.
Once Phases 1 and 2 were completed, G&S increased the VFD motor speeds to feed baggage more quickly into the EDS machines. The throughput rate was now 2,448 bags per hour, safely above the peak SWA requirement of just over 2,000 bags per hour.
However, this higher throughput resulted in increased network traffic and dangerously challenged the already fragile upper level controls system; ie, the sortation allocation controller (SAC) (the system’s ‘brain’). “The upper level control system was already prone to failure and was causing the whole system to fail. It was a big issue: at a certain baggage volume the SAC ‘brain’ would fail causing the system to gridlock, and bags would start missing flights,” explained Jonathan Hill, Project Manager and Lead Designer, VTC.
Keeping the old sortation allocation controller from melting down until it could be replaced required a lot of teamwork, communication and vigilance, Mr Hill says. “The old sort controller was cleaned up and the memory was optimised to the extent possible, but the biggest way we got around this was working with SWA and TSA to identify problems as they arose, keep lines of communication open and using the proven contingency plans SWA had in place, such as who to call to get things moving again. “Understanding the breaking point of the CBIS as associated to baggage volume was important. We reduced surprise failures by knowing when peak days and equipment failures coincided and when to run the drop-and-go system [to ease the strain on the SAC].”
In Phase 3, scheduled for completion this April, VTC installed a much more robust control system. In the new set-up, the Programmable Logic Controllers, which are less prone to failure, do all of the ‘heavy lifting’, which greatly reduces the burden on the upper level system. Mr Hill relates: “A major feature of this project is replacing the sort controller to improve diagnostic features, such as enhanced reporting which gives us the ability to better monitor system performance. This also provides the operator with the tools to troubleshoot problems that may impact system performance; for example, loose photo eyes or slipping belts. We are adding a lot of reporting, which will make the CBIS compliant to the TSA 4.1 Planning Guidelines and Design Standards (PGDS) for Checked Baggage Inspection Systems.”
Phase 3 also included the renovation of the CBRA. This included new PGDS-compliant stainless steel search tables, new bag tag readers and a motorised security door which provides a much more ergonomic means of baggage loading for the TSA. VTC also replaced obsolete baggage removal point and baggage inspection table human-machine interfaces with PGDS 4.1 compliant VersaView equivalents. Adding e-stop control stations also provides the TSA with a safer, more functional working environment.
“A project like this is never easy, but this is a great example of how well a plan comes together when everyone is working toward the same goal,” Mr Hill emphasised. “There is always a concern when you are modifying an operational system, but Southwest Airlines, Maryland Aviation Administration and the Transportation Security Administration all worked together to get this done.”