European guidelines for vertiport designs

Just a few weeks after the published draft for vertiport standards issued by the FAA, the European Union Aviation Safety Agency (EASA) published their 'Prototype Technical Design Specifications'. Whilst my previous article on the FAA standards focuses on the differences between the published draft and EASA Heliport design standards, this article shows the main differences between EASA CS-HPT- DSN Heliport Design standards and both the Heliport standards and the vertiport standards of the FAA.

The Prototype Technical Specifications is a set of non-regulatory material for the design of vertiports. This set of guidelines applies to the SC-VTOL-01 eVTOL's, which are limited to 9 passenger seats and/or a maximum take-off mass of, 3175 kilograms. In a second stage, rules related to vertiports are considered to be in the scope of Regulation 2018/1139 with the corresponding Certification Specifications (CSs) and Guidance Material (GM).

Note: During the Amsterdam Drone Week, EASA will give a technical workshop on vertiports (Wednesday 30 March).

Physical characteristics

Looking at the physical characteristics of the vertiport design standards, the take-off and landing areas consist of a Final-approach and take-off areas (FATOs)?and Safety Area (SA). Based on the published (minimum) standards, the following applies for a Lilium Jet eVTOL with a wingspan of 13.9 meters and a maximum take-off weight (MTOW) of, 3175 kg (without taking the rejected take-off distance into account).?

FATO = 1,5 * wingspan = 1,5 * 13,9 = 20,9 m
Safety Area =  0,25 * wingspan = 0,25 * 13,9 = 3,5 m (at least 3 m)
FATO + (Safety Area * 2) = 20,9 + (3,5 * 2) = 27,9 m
Total area (square surface) =  27,9 * 27,9 = 778,4 m2

or
 
Total area (circle surface) = π * r^2 = π * 13,95^2 = 611 m2   
        

Comparison

Based on the Lilium Jet characteristics, I made a comparison of the FAA, EASA and the existing EASA Heliport standards:

• EASA vertiport standards: 778,4 m2 (square) or 611 m2 (circle)
• FAA vertiport standards (draft): 1739 m2
• EASA CS-HPT-DSN Heliport Design: 772,8 m2

Heliport v.s. Vertiport

It can be concluded that for this eVTOL, the EASA vertiport standards for square designs are almost equal to the EASA Heliport Design standards. However, it highly depends on the characteristics of the eVTOL. Comparing the heliport standards to the recently published EASA specification with a maximum dimension of 8 meters, the following applies:

EASA Heliport standards:

FATO = 0,83 ? wingspan = 0,83 ? 8 = 6,64 ???
Safety area = 0,25 ? wingspan = 0,25 ? 8 = 2 ???(at least 3m!)
FATO + safety area = 6,64 + 3 = 9,64 → at least 2 ? wingspan = 16 ???
Total area (surface) = 16 ? 16 = 256 ??2

EASA Vertiport standards:

FATO = 1,5 * wingspan = 1,5 * 8 = 12 m
Safety Area =  0,25 * wingspan = 0,25 * 8 = 2 m (at least 3 m!)
FATO + (Safety Area * 2) = 12 + (3 * 2) = 18 m
Total area (square surface) =  18 * 18 = 324 m2

or

Total area (circle surface) = π * r^2 = π * 9^2 = 254 m2
        

In this case, it can be seen that the difference is more than 20% for squared areas. Where both the Heliport and EASA vertiport standards require a safety area of at least 3 meters, the determination of the total area (FATO + Safety Area) is defined differently. However, since the vertiport design standards also highlight round designs, the total area can be reduced. Therefore, it is important for the UAM industry, cities, municipalities, and provinces in Europe to assess the physical impact of the vertiport specifications since the dimensions can significantly differ. In this way, the industry is able to move forward enabling Urban Air Mobility.

EASA v.s. FAA

Comparing the EASA standards with the recently published draft of the FAA, the differences can be enormous (again). Also, in the case of the example provided above, the total dimension based on the FAA standards is still 40% larger. The FAA uses a factor 2 for the determination of the FATO whilst EASA published a factor 1,5. Another main difference is the determination of the safety area. Where FAA does not use a minimum (instead of the 3 meters of EASA), the determination only depends on the eVTOL characteristics. For small eVTOLs this means the impact of the FAA standards is less or even equal (refer to the example below for an eVTOL dimension of 4 meters which equals the CD).

FAA Vertiport standards:

TLOF = 1CD = 4 
FATO = 2CD = 2 * 4 = 8 m
Safety Area = 2 * ?CD (added to edge of FATO) = 2 * 2 = 4 m
Total = 3CD = 3 * 4 = 12 m
Total area (Surface) = 12 * 12 = 144 m2

EASA Vertiport standards

FATO = 1,5 * wingspan = 1,5 * 4 = 6 m
Safety Area = 0,25 * wingspan = 0,25 * 4 = 1 m (at least 3m!)
FATO + (Safety Area * 2) = 6 + (3 * 2) = 12 m
Total area (Surface) = 12 * 12 = 144 m2

or

Total area (circle surface) = π * r^2 = π * 6^2 = 113 m2
        

Conclusion

The impact of the recently published standards of both the FAA and EASA vary. Also in relation to the existing heliport standards, the impact differs. For larger eVTOL's, the standards published by the FAA (draft) requires more space, whilst for small eVTOL's the impact can be equal.

However, the specifications related to dimensions of EASA are not limited to take-off and landing areas. Just like with the Heliport standards, guidelines have been drawn up for parking stands and taxi routes.

I'm looking forward to seeing all developments in the coming months to enable UAM. If you have any comments or questions, feel free to contact me.