Helicopter IFR Technique: Communications – Negotiating Altitudes 

Helicopters represent a very small percentage of IFR traffic and therefore are often handled like fixed-wing aircraft unless pilots specifically request to be treated otherwise. Since there are many situations in which a helicopter pilot may want to fly IFR lower than most fixed-wing aircraft, they will likely need to request to fly at an alternate altitude.  

Whereas fixed-wing aircraft are often more efficient at altitude, more likely to be pressurized, and more likely to have equipment that allows them to operate in icing conditions, very few helicopters have deicing capability, and helicopters are generally unpressurized. Furthermore, because helicopters have slower airspeeds, winds aloft can also have a much greater effect on groundspeed, efficiency, and range. As such, helicopters usually benefit from remaining lower than their fixed-wing counterparts. 

The first opportunity to communicate that lower altitude preference is through the IFR flight plan. 

The altitude entered in the flight plan tells ATC your requested cruising altitude. Clearances are normally based on the route and altitude filed, although ATC may assign something different because of terrain, traffic, routing, or local procedures. 

In many training environments, instructors tell students to file the highest altitude they expect to encounter during the flight. Although that may work well for airplanes, it can communicate the wrong request for a helicopter. 

In the southeastern United States, where I received my initial instrument training, it is often possible to complete an entire flight at 3,000 feet. That altitude is generally not problematic for a helicopter. 

The West Coast can be very different. A route may begin with minimum IFR altitudes near 3,000 feet and require altitudes approaching 10,000 feet an hour later. 

If you file for 10,000 feet, you are telling ATC that 10,000 feet is your requested cruising altitude. ATC will likely begin moving you toward that altitude much earlier than necessary. 

If you file 3,000 feet, you communicate that you would prefer to remain low. You still need to plan for the climb because ATC will ensure you reach 10,000 feet before the route requires it. Remaining lower during the first portion of the flight, however, may help you avoid icing, an oxygen requirement, or a strong headwind. 

Your filed altitude begins the conversation. It does not end it. 

Once airborne, altitude is often negotiable. 

Controllers generally work within an established directional altitude structure, with odd altitudes used for eastbound traffic and even altitudes for westbound traffic. In controlled airspace, however, pilots fly the altitude assigned by ATC. The regulatory odd-and-even IFR cruising-altitude rule applies specifically when operating in uncontrolled airspace. 

Facility procedures can also influence the altitudes you receive. Air traffic control facilities use letters of agreement to establish the routes, locations, and altitudes at which aircraft are normally transferred between controllers. 

When an aircraft crosses a facility boundary in accordance with those procedures, the handoff may require very little additional coordination. An altitude outside the normal flow may require the controller to coordinate directly with the next sector or facility. 

For example, if Seattle Center passes off aircraft coming from the north at a specific waypoint and in a specific altitude block to Portland Approach, no coordination is necessary. If they vary from the standard operating procedure they are required to pick up the phone and coordinate your transition which increases workload at both facilities.

That does not mean you should avoid asking. It means you should make a clear request and, when useful, provide a concise operational reason. Asking early to stay ahead is always appreciated by ATC. 

For example: 

“Seattle Center, NXXXAB, request three thousand as long as practical due to potential icing 4000 and above.” 

Or: 

“Seattle Center, NXXXAB, request eight thousand until BRUTE to decrease headwinds.” 

The reason does not need to become a long explanation. A few words may help the controller understand the request and determine how best to accommodate it. 

If you know ATC cannot approve the altitude right now, you can still ask them to consider lower in the future: 

“NXXXAB, when able, request three thousand.” 

Helicopter pilots should recognize that a special altitude request may create additional coordination for the controller. They should also remember that ATC is providing a service, and helicopters are legitimate users of the IFR system with performance characteristics and operational concerns that differ from those of most fixed-wing aircraft. 

Be respectful of the controller’s workload, understand the controller’s constraints and comply with every legal and safe altitude assignment you receive. 

But ask for what you need. 

Helicopter pilots should not automatically accept the standard fixed-wing fare when a different altitude would make the flight safer or more efficient.