Just about everything written so far about domestic RVSM seems to be focused on ways operators can comply with the upcoming requirements by next year’s January 20 deadline. But what about business aircraft operators who have no intention–at least not right away–of spending the thousands of dollars for equipment upgrades, Service Bulletins, aircraft skin mapping and DRVSM flight checks? If operator surveys are to be believed, a surprisingly large number plan to forego approvals until after they have experienced for themselves how hard it is to get around (or, rather, over) the soon-to-be-restricted airspace.

As most business jet pilots know by now, domestic reduced vertical separation minimums will cover FL290 to FL410. But the rules also include a provision allowing non-DRVSM-compliant airplanes to climb through the airspace and cruise on top. Since this option is available, many operators appear to be waiting for DRVSM to start to test how well it works in the real world.

The FAA has warned that this loophole may not be an option in all instances, especially in traffic-dense areas or when weather begins to wreak havoc on ATC flows. This will mean having to fly below DRVSM levels, where fuel is burned at a faster rate and encounters with storms, turbulence and crowded air space are more likely. In some parts of the country, controllers may never allow a non-DRVSM-compliant airplane to transition through the airspace, preferring to keep those airplanes bunched together in the middle flight levels.

But given the choices between added fuel burn and a $100,000 (or even $200,000) bill for DRVSM modification work, some operators may decide it is worth the added expense and hassle to accept the consequences of flying lower. For airplanes such as older Citations and Diamonds, which regularly fly at FL330, it would probably take two or three years to spend $100,000 on the additional fuel burned flying below DRVSM airspace, say pilots.

On the other hand, many airplanes can easily climb above DRVSM airspace. These operators apparently are planning to put ATC to the test next winter, reasoning that since controllers try to keep business jets from mixing with airline traffic in the first place, they will gladly send Part 91 and 135 traffic higher. While these options may seem enticing, experts warn the approach could actually end up being a big mistake.

Modifying older models for DRVSM is proving the toughest challenge. While newer aircraft benefit from certification solutions that have been developed by their respective airframe and avionics manufacturers, some older airplanes are being left out in the cold. A handful of types are not being certified under “group” status because of their limited numbers, and this means they are proving far tougher to bring into compliance. Others can be upgraded without too much trouble, but the cost for new air-data computers, altimeters and other equipment can be steep.

Yet the alternative that many think makes the most sense is to hold off on DRVSM work until after the rule takes effect. If it turns out that ATC will not allow non-DRVSM-compliant airplanes to climb through the airspace, operators might then start on the road to compliance. At that point, so the argument goes, the majority of business jets will have completed the process and demand for DRVSM avionics will be much lower. And as anyone who’s taken an introductory economics course knows, as demand falls so do prices. That $100,000 bill for DRVSM work may turn out being $75,000 or even $50,000 next spring when avionics shops are less busy and avionics manufacturers start dropping their prices.

The hole in the argument that says ATC will allow non-compliant airplanes to transition through DRVSM airspace is that controllers have to be concerned that they may not be able to get those airplanes back down without major headaches if DRVSM-compliant aircraft are operating nearby. FAA officials have said that some controllers may simply be unwilling to allow non-compliant airplanes to climb higher than FL270, particularly on busier flight routes.

For many, however, what the DRVSM dilemma really comes down to is a belief that avionics prices will start to drop after the rule goes into effect. But unless you fly one of the few airplanes that is still relatively efficient operating below FL290, before long the money you spend on extra fuel will probably equal what you would have spent for DRVSM modifications.

“I hear this rationale every day,” said Don Tinker, an independent RVSM consultant based near Dallas. “You can’t convince me that it’s a good idea to wait. All you have to do is make 10 or 15 trips in most airplanes and you have paid for the difference of the maximum that you would have saved if you waited. And then let’s say you sell your airplane. The person buying it is going to deduct the cost for RVSM right off your asking price. So now you are almost at the break-even point where you could have upgraded for DRVSM, and the buyer deducts $80,000 off the price of your airplane. You don’t gain anything.”

Tinker, a Beechjet 400 captain for a Texas flight department, said there are certain airplanes that cannot wait for DRVSM to take effect to make necessary modifications because these airplanes are so inefficient below FL290. These aircraft include the Learjet 24, 25, 31, 31A, Beechjet 400A and Falcon 20, 50 and 900. For example, a loaded Learjet 31A has less than a 1,200-nm IFR operational range at FL430. At FL290, the range of that same airplane is significantly reduced, meaning not only paying more for additional fuel, but having to make extra stops along the way.

A Frost & Sullivan survey released in January and paid for by avionics maker Innovative Solutions & Support found that while between 4,000 and 6,000 business jets do not yet comply with the requirements of RVSM, only 2,400 are expected to be upgraded by next January 20. That leaves at least 1,600 airplanes in non-compliance after the deadline, a situation that could cause problems for operators if ATC indeed keeps them below DRVSM airspace.

“What a nightmare that would be,” Tinker said. “If that scenario plays out, you will probably end up with ground delays if you file for FL270. Airplanes will be absolutely nose to tail on some routes right across the country.”

Tinker’s company, RVSM Consultants, helps flight departments on the long and often arduous road to RVSM approval. Because RVSM reduces vertical separation of airplanes from 2,000 feet to just 1,000 feet, it requires height-keeping checks and in most cases upgraded avionics that are more precise than older equipment.

The company currently is assisting three international clients and about 20 domestic flight departments, performing just about every conceivable task that would normally be left to the chief pilot or flight department manager. This includes writing the initial letter of request to the FAA; researching the required SBs and finding the correct STCs for compliance; developing a DRVSM maintenance program; assisting in applying for and completing a GMU test flight; providing required DRVSM ground school for the pilots; and writing a DRVSM policy/procedures manual.

And that does not include the actual work that needs to be performed by a service center to upgrade avionics and map the airplane’s skin in the areas around the static ports and pitot tubes. With so much hassle and expense involved in gaining operational approval for DRVSM, it is no wonder that some operators are holding off as long as possible. Tinker said he thinks the majority of the holdouts will be forced to comply not long after DRVSM takes effect, once they see life without that golden ticket is unbearably difficult.

“I would bet that 80 percent of them complete the process within 90 days after the start of DRVSM,” said Tinker. “Within 90 days of next January 20, those operators will have storm issues, and range issues, and ATC will not be able to help them out, especially on the East Coast.”