GoKawiilOn the 24th of September that year, a controller manning the tower’s helicopter control position — more on that in Chapter 4 — cleared a helicopter for liftoff from DCA’s north helicopter pad, which no longer exists but was at that time located just west of the departure end of runway 1. The helicopter belonged to a civilian operator that had somehow acquired the special military chart, so the pilot requested a departure via “Route 1 to Greenbelt.” I was never able to find a copy of this more than 40-year-old military chart, but if Route 1 was the same as it is today (and the evidence supports that it was), then the route presumably ran from Cabin John, Maryland, southeast down the Potomac River to Hains Point, immediately north of DCA, then northeast up the Anacostia River to Greenbelt, Maryland. Since the DCA north helipad was not located directly under Route 1, a departure via this route would have required what’s called a “transition,” in which the helicopter follows a normal agreed-upon path to, from, or between a published route or routes.[28]
The helicopter controller said that she always told helicopters departing the north helipad for Route 1 to fly northwest to the Arlington Memorial Bridge, where they could intercept the route and follow it to their destination without interfering with traffic taking off or landing on runway 1/19 (then known as runway 18/36). This transition was informal and not published on the special military chart. In this case, when the helicopter pilot asked for Route 1 to Greenbelt, she cleared the helicopter to fly as requested, but incidentally forgot to specify the transition that should be used. As a result, the helicopter pilot assumed he had been cleared to Route 1 by the most direct transition, which took him directly over the departure end of runway 36 (now 1).[28]
At the same time, the Local controller, who was responsible for issuing landing, takeoff, and runway crossing clearances, cleared an Eastern Air Lines Boeing 727 for takeoff on runway 36 without coordinating with the helicopter controller. As the 727 neared its decision speed, the pilots suddenly saw the helicopter take off from the north helipad and fly toward their projected takeoff trajectory. At the last second, the captain aborted the takeoff and slammed on the brakes. Simultaneously, the helicopter pilot saw the 727 approaching and steered hard away from the runway, back toward the helipad. Behind him, the speeding 727 ran off the end of the pavement and lurched to a stop in the grass, just 40 meters from the edge of the Potomac River.[28] By the narrowest of margins, disaster was averted.
The NTSB found that the helicopter operator didn’t have an LOA with the tower authorizing its pilots to request or accept clearances based on the special military chart, but that the controller had no way of quickly ascertaining this. Furthermore, because it wasn’t intended for civilian use, the chart only depicted standard transitions to and from military heliports, excluding civilian helipads like the one at DCA. As a result, the NTSB recommended that the FAA create a single VFR helicopter route chart for use by all helicopters in the DC area, both military and civilian.[28]
Because the special military chart is, as far as I can tell, lost media, I wasn’t able to definitively establish the closeness of the relationship between the pre-1985 military chart and the Baltimore-Washington VFR Helicopter Route Chart that the FAA published in 1986 at the behest of the NTSB. However, I have plenty of reason to believe that the helicopter routes themselves were most likely adapted with few, if any, significant alterations.
One reason why I believe the helicopter routes were either copied directly from the military chart, or were otherwise designed mainly to accommodate the needs of the Department of Defense, is that Route 1, the route to Greenbelt requested by the incident helicopter pilot and the only special military route specifically discussed in the NTSB report on the 1985 incident, still leads to Greenbelt today.[27]
Another reason is that the US military was by far the largest helicopter operator in the DC area at the time and still is today, accounting for 79.2% of all helicopter traffic using helicopter routes within 5 nautical miles of DCA.[1:200] This is largely because civilian and law enforcement operators mostly don’t fly from a fixed point A to a fixed point B. Police and news helicopters tend to circle for long periods in a particular area in order to follow an event on the ground, and medevac helicopters have to fly to wherever the patient happens to be, which is usually nowhere near the handful of published helicopter routes. Military helicopters, on the other hand, are there to fulfill specific missions, requiring them to fly between the same points over and over again.[3–3:08:00] As a result, the FAA added “police zones” to the chart, allowing law enforcement and civilian helicopters to circle inside a particular area with defined boundaries that can keep them separate from helicopters that might be circling in other zones. These zones deliberately avoided overlapping with some of the major helicopter routes, emphasizing the distinct operating models they were designed to accommodate.[27] Therefore, there would have been few stakeholders in the helicopter route design other than the US military.
The identity of the organization that first drew the helicopter routes — and I do believe it was the Department of Defense — is important because it helps explain some of the glaring shortfalls in the route design. But before I discuss those problems, we need to look at what exactly a helicopter route is, in the legal sense.
Each helicopter route is depicted on the chart as a wide blue line that typically follows a visually distinctive route, such as a river or a highway or a chain of specified landmarks. Although the blue lines bear some resemblance to a corridor of airspace, they’re purely illustrative, because the routes don’t actually have defined lateral boundaries. For example, the pre-accident route chart stated that Route 4 should be flown “via the east bank of the Potomac River,” but nowhere did it say how close to the east bank one needed to be, nor was any similar information provided for any other route either.[1:46] The routes did include specified altitudes, although the chart contained contradictory information. An info box labeled “recommended route altitudes” stated that an altitude with a line under it was a minimum, an altitude with a line over it was a maximum, and an altitude with both lines was “recommended,” while a separate info box said “all altitudes are maximum,” leaving it unclear whether any altitudes were recommended or mandatory.[1:45]
Press enter or click to view image in full size Detail of the immediate DCA vicinity on the Baltimore-Washington VFR Helicopter Route Chart as it appeared at the time of the accident. Source: FAA
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