Choosing the right “Design Aircraft”

When it comes to designing your helicopter landing area, perhaps the most important decision you can make is your design aircraft.
The design aircraft is the largest actual or future model machine that will use the landing area. Almost every regulatory instance that refers to the size of the facility and the associated airspace relates back to the physical size and performance of the design aircraft.
The design aircraft is typically the largest aircraft expected to operate at the heliport. In some circumstances, it may be a composite type of design aircraft where the gear dimensions and weight reflect one type of aircraft while the overall length or rotor size represent another. The net effect of this, if the conservative factors of the worse case situation are considered, is the facility is designed with no limitations for the aircraft it is intended to serve.

It is very important to consider a number of factors when choosing a design aircraft, including lifespan of the heliport, future technology and expanded usage.
As most permanent facilities can have a life span of 20 to 50 years, many heliport designers will consider a design aircraft that has staying power. For example, a hospital currently using BK 117s as their primary MedEvac aircraft may want to consider a larger design aircraft so the heliport will be able to support a future aircraft upgrade. If a heliport is built only to the size and weight standards of the BK 117, the cost to retrofit it for larger aircraft can be substantial.

For larger facilities, such as corporate and public use heliports, the FAA considers a helicopter the category of the Sikorsky S-92 to be a reasonable design aircraft as it allows for most helicopters currently flying as well as future technology expected in the next decade.

Another important consideration for choosing a design helicopter is the expanded usage of the heliport. In the case of a hospital heliport, for instance, it is imperative to consider the size of local search and rescue aircraft that may require access to the heliport for medical transport.

Since 9/11, and more recently Hurricane Katrina, the focus for hospital heliport design has shifted. The FAA is now recommending hospital heliports be designed to aid in the case of a disaster. In both 9/11 and after Katrina, military aircraft were used to transport injured people to outlying hospitals, however many existing hospital facilities did not have the heliport size to accommodate the larger aircraft.

Additionally, many National Guard and Army Reserve units have been called on in daily medical emergencies for helicopter rescue and medical transport.
Typically, the largest helicopter the military operates for MedEvac is the S-70 Blackhawk. This aircraft is about the same size and dimension of the S-92, so choosing the S-92 as a design helicopter can avoid a life threatening situation where a seriously injured or ill patient is turned away because the helicopter was too big to use the hospital’s heliport.

For corporate heliports, it is important to consider not only the corporation’s current helicopter, but future aircraft considerations and those flown by potential guests. Again, the S-92 makes for a very versatile design helicopter, not only because of its increased popularity with corporations, but also because a heliport designed to support one will support most other corporate helicopters in use today and the near future.

When it comes to cost, the increased expense of designing a higher capacity heliport into a new facility is relatively low if plans already called for a smaller heliport. The cost differences mainly come from increased column sizing, pad design and allowing for additional open space.

The real cost comes when a smaller design helicopter is originally built and retrofits become required to serve larger helicopters. Due to design loadings, pad sizes and needed clearances, the vast majority of lower capacity heliports require a full replacement in these instances. This reason alone is a strong argument to carefully consider a design helicopter and future uses of the heliport.

When working with my clients, I recommend any new or upgraded heliport, regardless of use, be designed for the class of helicopters recommended by the FAA in their Heliport Design Advisory Circular. Too many times final decision makers will opt for the smaller design helicopter to save money only to experience the full embarrassment of the heliport not being able to serve some aircraft, or worse, a critically injured patient turned away.