Posts by user "andihce" [Posts: 5 Total up-votes: 3 Page: 1 of 1]¶

There have been a number of references above to the woefully inadequate vertical separation provided between helicopter Route 4 and the approach to Runway 33. Given altimeter errors (expected and maybe not so expected) in the helicopter, a helicopter flying high (and possibly offset sideways towards the end of Runway 33) and an aircraft maybe low on approach, there really wasn’t any guaranteed separation.

I strikes me that, from my layman’s point of view, that this is the primary and gaping hole (among numerous others) in the Swiss cheese here.

At the same time, I get the sense that no controller was ever going to intentionally permit a helicopter to pass directly under an approaching aircraft and challenge that limited clearance.

My question is, should this have been (or was it?) formalized as an ATC procedure? Because if this had been proceduralized, I find it hard to believe that just nighttime VFR separation would have been found acceptable in that environment. Rather I would think that lateral separation should have been actively managed by ATC.

For one thing, with the CRJ (or whatever aircraft) pilots making a late switch to 33, turning to line up with the runway, etc., they may not have had the bandwidth to scan for a possibly conflicting helicopter, if they could even have seen it from their cockpit. (IIRC from the inquiry, the NTSB will be investigating that last point.)

I don’t know how difficult it may have been for the helicopter to see the CRJ, but the simple fact is that they did not.



On another subject, one thing that struck me from the inquiry was that the helicopter pilot apparently had very limited recent flight time, yet was assigned a challenging check ride.

This contrasted with the testimony of the leader (?) of one of the local Medivac groups, who discussed how much more experience he and his pilots had flying in that challenging environment (and often single-pilot ops at that).

Is the Army not providing adequate training and flight time to ensure their pilots can operate safely in those conditions?

I understand the point about constant relative position, but this "collision criterion" is generally stated for two objects maintaining constant relative velocity (constant course and speed) and heading.

The CRJ was executing a left turn for some distance up until the point of collision, while the helicopter was flying a fairly straight course. Under the actual conditions, the azimuth of the CRJ as viewed from the helicopter should have shifted significantly as the collision point was approached.

And yet as we saw, this approach failed. So something has to be wrong with it.

Yet was not the controller required to inform the CRJ of the helicopter, which (as the inquiry noted) he failed to do? Thus a possible cross-check was lost.

That would perhaps be a standard definition of "normalization of deviance". But I think there is a possible extension of that definition, which allows for the procedure to be flawed or open to interpretation, and considers "deviance" as departure from safe operation , even while the procedure is technically observed. It could also be the case that the procedure was initially valid, but became marginal as a result of changes in its area of application since its inception.

Each time someone gets away with a close call, the "normalization" sweeps the issue under the rug, instead of the procedure being questioned. The longer the procedure is in use, the more confidence there may be that it is acceptable, when in fact it may just be a matter of time until some unlikely and disastrous event occurs "by chance".

Having worked in a non-aviation area that became heavily proceduralized after all too many mistakes had been made, I have seen more than a few flawed procedures that continued to be employed despite warning signs, typically because of time, management, cost, etc. pressures. Modifying and reviewing a procedure can be a time consuming process as many individuals and management structures can be involved in a complicated system.

In the present case (without knowing exactly what procedures were in effect), I could argue that permitting visual separation at night in this particular environment was a key procedural flaw. But it was accepted as there had been no accidents as a result, even as perhaps traffic density, etc. increased risk over time.

Hopefully he knows more about aircraft rules than maritime rules. In maritime parlance (to adopt his analogy), the CRJ would be the "stand-on" vessel (expected to maintain course and speed); the Blackhawk would be the "burdened vessel", responsible for taking avoiding action (giving way).