As DRVSM deadline nears, compliance pressure grows

Aviation International News » July 2003
July 30, 2008, 7:32 AM

In spite of the near panic the subject of DRVSM creates in some flight departments, it may come as a surprise that the FAA lists only three things an operator must have to gain access to the future stratum of special-use airspace: an airplane; the telephone number of your local service center; and money.

So went the line that got the biggest laugh at last month’s DRVSM seminar in Chicago, an FAA-hosted event that was meant to serve as a primer for business jet operators about to embark on the long and sometimes confusing road to obtaining an RVSM letter of authorization, the golden ticket to the airspace between FL290 and FL410 after Jan. 20, 2005, the date DRVSM is to take effect.

While the quip by an FAA staffer to a group of about 100 pilots and other aviation-industry pros was meant to inject some humor into a complex–and often contentious–subject, it also contained an important kernel of truth: if you’re worried about the process for obtaining an RVSM approval, then by all means get help from a qualified maintenance outfit that has experience dealing with RVSM.

After all, mod centers by now know exactly who to talk to and where to go to satisfy the requirements. From component manufacturers and OEMs to the local FSDO official who will put his stamp of approval on your aircraft upgrade package and RVSM maintenance program, a service center’s trained personnel can serve as welcome liaisons.

But you’d better make that call soon, warn insiders, because schedules are predicted to start filling up fast as 2005 approaches.

“If you haven’t started taking a hard look at RVSM by now, you are seriously behind the power curve,” said Bob Lamond, NBAA manager for air traffic service issues. NBAA pushed hard for a phased-implementation schedule that would have introduced DRVSM in baby steps over the next several years. Airlines and controllers pushed back harder, and in the end the FAA decided to introduce DRVSM all at once in January 2005 so as not to delay cost benefits to the airlines, by far the biggest user of the affected airspace. (The FAA predicts fuel savings of about $5.3 billion through 2016, a sum that works out to about $500 million per year. Most of the savings will come from the addition of six new flight levels at the most fuel-efficient altitudes, where airliners make up nearly 90 percent of the traffic.)

The final rule authorizing the introduction of reduced vertical separation minimums in domestic U.S. airspace has been signed off by FAA Administrator Marion Blakey and is on a fast track through the Department of Transportation and Office of Management and Budget. It should emerge in the coming weeks. For those operators who have balked at taking RVSM seriously until the official updates to the FARs are made, that final excuse for inaction is about to evaporate into the ether of the DRVSM flight levels.

Your only choice now is to go ahead and gain RVSM approval or be content flying most of the time at FL270 and below, where jets greedily gulp fuel as though it were pitchers of ice water on a hot summer day.

The Price of Inaction

It’s worth noting that crews may request a climb or descent through DRVSM airspace and can cruise on top for as long as they’d like. But it’s also important to point out a few practical problems with this plan that make it almost unworkable. First, a climb above DRVSM means a climb to FL430 (2,000 feet above the highest RVSM flight level). If conditions are less than favorable or the airplane is a little heavy and the crew has to ask the controller to level off at FL410 to burn fuel, they will immediately be given a descent to FL270 or lower to get the airplane out of DRVSM airspace–not exactly the most efficient flight profile.

Second, it makes a controller’s job that much more difficult to have a non-RVSM compliant airplane trying to climb or descend through a particular sector, especially if traffic is heavy or adverse weather enters the mix.

“The nightmare scenario is if you suddenly have a couple of non-RVSM aircraft to accommodate while vectoring everyone around a line of thunderstorms,” said Steve Creamer, en route and terminal operations manager with the FAA in Washington. Controllers have enough to worry about without the added complexities of maintaining 2,000 feet of separation for a few airplanes and 1,000 feet for all others, Creamer said. (This, by the way, is the reason the air traffic controllers union lobbied hard against phased implementation of DRVSM.)

A persistent rumor has been circulating for several months that DRVSM could be delayed. True is the FAA’s pronouncement that unless 90 percent of all traffic that routinely flies between FL290 and FL410 has gained approval by Jan. 20, 2005, DRVSM will indeed be postponed. But considering that only about 10 percent of all flights in the airspace between FL290 and FL410 are general aviation operations (many of them already RVSM approved) and airlines are firmly behind the concept, a delay is unlikely, say FAA officials.

In fact, controllers may start using “tactical RVSM” on a limited basis as early as this summer in airspace where lots of RVSM-approved airplanes routinely operate. Canada and Mexico, which will implement RVSM on their borders the same day the U.S. flips the switch, have indicated they will be ready as well.

Gaining RVSM Approval

The first step in the RVSM approval process is a telephone call. Once an operator has decided that it intends to seek an approval for its airplane, a call needs to be made to the aircraft manufacturer or a qualified service center (see box below). The most important question to ask is whether the airplane is considered a group or non-group airframe.

The majority of airplanes are eligible for group approval, meaning other airplanes of the same type have already proved their capabilities through test flights, airframe checks and avionics modifications. No further test flying of group aircraft is required to gain RVSM approval.

Non-group airplanes, on the other hand, must fly with booms or trailing cones to monitor the performance of air-data systems, autopilot and altitude alerter and may require substantial modification to meet requirements.

Several factors can lead to an airplane being considered non-group. The most obvious is the case where no group certification exists because too few airplanes are in operation or group status is not possible due to the type’s technological shortcomings. But there are other reasons an airplane could fall into the non-group category. If an avionics installation varies significantly from the production standard or airframe modifications have been made, for instance, the FAA may require flight testing under non-group rules of the individual airframe before an RVSM LOA will be issued.

To gain approval for operations in RVSM airspace an airplane must be equipped with an autopilot, altitude alerter, transponder (per FAR 91.215) and two independent altimetry systems that are capable of maintaining altitude to strict tolerances. TCAS is not a requirement of RVSM, but if an airplane is already equipped with TCAS II it must include Change 7 software to be eligible for RVSM approval.

The autopilot must be able to hold altitude within 65 feet of acquired altitude and the altitude alerter threshold must not exceed ±300 feet for older airplanes and ±200 feet for airplanes type certified after April 9, 1997. Operators will need to prove these tolerances by flying a GMU or HMU test flight within six months of receiving their RVSM LOA. A GMU is a piece of hardware that flies on board the aircraft during the height-monitoring flight, while an HMU is a ground station that the airplane must fly over. Service centers can arrange for GMU or HMU flights.

Even if an airplane is considered part of a group, it can still experience difficulties during the approval process. For example, a service center will perform what is known as a skin-waviness check during the approval process to make sure the aircraft surface near the nose is smooth and incongruities will not affect height-keeping accuracy.

“It’s amazing how small a dent or paint chip around the static port can have an effect on height keeping at 41,000 feet,” said Bill Schinstock of the FAA’s certification branch in Wichita.

In addition to the technical requirements for the airplane, the FAA requires a recurrent training program for pilots who fly in RVSM airspace. A document called 91-RVSM is a must-read reference for operators who decide to develop their own RVSM training programs and manuals or who want a detailed understanding of the type of training the FAA requires. The document can be found on the Web at: www2.faa.gov/ats/ato/150_docs/ 91RVSM_CH1.doc (take special note of appendix four and five).

Domestic U.S. RVSM practices and procedures are still under development, but they will include contingency procedures; weather-deviation procedures; track-offset procedures; flight planning; pilot training for the use of TCAS Version 6.04a or Version 7.0 in RVSM airspace; TCAS II Version 7.0 modifications; and dispatcher guidance for RVSM operations.

Operators must also submit an RVSM maintenance and inspection program to their FSDO, which includes any maintenance requirements that are defined in the approved OEM data package. This will be used as part of a continuous airworthiness maintenance program approval or an equivalent program approved by the local FSDO. All RVSM equipment should be maintained in accordance with the component manufacturer’s maintenance requirements and performance requirements outlined in the approved data package. Any modification, repair or design change that alters the initial RVSM approval in any way is subject to a design review by the FSDO. Maintenance practices that affect the continuing RVSM approval integrity (such as the alignment of pitot/static probes, dents or deformations around static plates and so on) should also be reported to the FSDO.

The FAA plans to hold more DRVSM seminars in the future. Dates and locations are September 9 and 10 in Seattle; February 4 and 5 in Dallas and, if needed, in April or May next year. Also on the schedule is a DRVSM seminar for FAA inspectors this September.

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