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To teach an old bird new tricks ...

As on every other evening, a muddy shroud engulfed Djibouti City - a sinister com bination of the last rays of sunlight illuminating every bit of airborne African dust. 'Looking down from an aircraft, it looked like fog, and this period of thermal crossover wreaked havoc on the eyes. Mountainous terrain, albeit several miles distant, rose silently out of the layer to the South and West. The city's lights, usually a welcome guide for any aviator, waited for the sun to fully set before they would reluctantly appear.

Into this quagmire we descended in our P-3C Orion, returning home after another long day in the AFRICOM area of responsibility (AOR). Ten hours prior, as the sun had risen, we had rotated away from this very airfield, out to conduct tasking in support of our Horn of Africa mission set. While the mission had been a success, the long flight took its toll on the aircrew, and now all eleven souls on board were looking forward to a post flight visit to the mess hall.

However, the terminal phase of flight at Djibouti International Airport (HDAM), rather than serving as a feel-good welcome mat, often posed the greatest threat to P-3 aircrews during our missions.

Although it is a NAVAID-equipped ICAO airfield, HDAM is without radar services. Its controllers must base their air picture entirely upon what aircraft pass to them, and there are a large number of dissimilar aircraft and UAVs operating in close proximity. The language barrier of the native controllers is an ever-present challenge, and it's always an all-hands-on deck communications evolution throughout the entire approach and landing.

We listened intently to the radios, trying to decipher both ATC directions and other aircraft's position reports. Nothing seemed amiss until we made the procedure turn inbound on the VOR approach, at which point we overheard ATC giving approach clearance instructions to a quickly incoming civilian airliner. The immediate cause for concern was that they were cleared to intercept the final approach course for the same approach that we were on... at the same altitude.

The air traffic control tower had, in effect, forgotten about us.

As we were mid-turn, we had neither the aft radar coverage nor any visual contact with the rapidly gaining and descending airliner. On earlier deployments, only rapt attention to radios and a prompt query of ATC could have saved our aircraft from a midair collision with that airliner, whose pilot was almost certainly on instruments in those abysmal environmental conditions.

Luckily, we had a tool in our repertoire that no other P-3 had brought to the fight: a fully integrated Traffic Alert and Collision Avoidance System (TCAS).

When Patrol Squadron NINE (VP-9) deployed last November, we took with us the first two TCAS equipped P-3Cs in the Fleet. We fully expected TCAS to provide a much-needed boost to situational aware ness and safety of flight in our expeditionary area of responsibility. After just the first month of operational use, however, TCAS had already proven to be a game-changer in the way our aircrews remain safe.

TCAS had picked up the transponder signal of the approaching airliner at nearly 40nm away and had shown its decreasing altitude and distance the entire way in. Once we heard ATC clear them for the approach, we were immediately aware of the danger afoot. We took it upon ourselves to politely notify ATC that we were "procedure turn in-bound, level 32 hundred feet." ATC, to their credit, had us "execute an immediate right 360" while the oncoming airliner was directed to "maintain five thousand feet until the final approach fix." The threat of collision was avoided before it fully materialized. This experience, and dozens like it, helps to reinforce the important edge that TCAS provides.

Though the FAA required commercial aircraft to equip TCAS as early as 1993, the Maritime Patrol and Reconnaissance Force (MPRF) community has only recently begun implementation of the system. Over the Horn of Africa, the first TCAS-capable P-3s have made their debut. MPR aircrews only had radios, radar, and vigilant observers to keep them from tangling with other airborne assets. Thanks to the diligent efforts of our community leadership and acquisitions team, we are now able to employ this SA multiplier.

The full benefits of TCAS are numerous and range across the entire spectrum of MPRA operations. We are now able to identify and correlate air traffic not initially observed (or perhaps ever visually gained). We can remain aware of traffic not broadcasting on safety-of-flight frequencies or far outside of controlled airspace. We can track terminal area traffic not identified or incorrectly referenced by air traffic controllers who are heavily radar-limited. Perhaps most importantly, we can successfully make informed, time-critical decisions in regards to overall aircraft positioning when dealing with in-flight malfunctions or emergencies.

Now, as our community shifts to rely on the P-8 Poseidon as our primary platform, P-8 aircrews will use a full suite of state-of-the-art avionics, including a fully integrated TCAS system. The incorporation of TCAS in the P-3, along with myriad other avionics upgrades in recent years, provides yet another link between platforms for a community in its first transition in a half century, while allowing us to operate our legacy aircraft more safely until their eventual sundown.

For the MPRF, TCAS provides the proven benefits available for many years to commercial aircraft, and a control to reduce the risk highlighted by a number of near-midair collisions that our community has experienced in preceding years. To the combat aircrews of Patrol Squadron NINE, a TCAS-modified aircraft delivers the heightened airspace awareness required to safely conduct flight operations in a high-risk, high traffic AOR and satisfies a long overdue MPRA need.

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Title Annotation:Traffic Alert and Collision Avoidance System
Author:Hawbaker, Kris; Pierce, Brandon
Geographic Code:6DJIB
Date:Sep 1, 2015
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