eVTOL GNSS Navigation: Requirements for Urban Air Mobility

Q: What GNSS accuracy does an eVTOL need?

Centimetre RTK: 0.6 cm + 0.5 ppm horizontal on mosaic-X5 and mosaic-G5 hardware, initialising in under 10 seconds. Accuracy alone is not enough for an aircraft - integrity monitoring and interference rejection matter more than a marginal accuracy gain.

Q: Is RTK required for eVTOL navigation, or is PPP enough?

PPP gives decimetre accuracy with wide-area coverage and no base station, which suits en-route navigation. Vertiport approach, hover and landing need RTK repeatability and fast convergence. Many Septentrio mosaic-family receivers support both, so PPP is a sensible fallback if the correction link drops.

Q: How do you keep a GNSS fix in a dense city?

Handle interference before the tracking loops see it: AIM+ suppresses interfering signals up to 60 dB, while multi-frequency multi-constellation tracking keeps enough measurements for a fixed solution under partial sky view.

Q: Can a GNSS receiver detect spoofing on its own?

Partly. OSNMA authenticates Galileo signals cryptographically and RAIM+ reports an integrity alarm when redundant measurements disagree. No receiver catches every scenario, so feed its alarms into the aircraft's failsafe logic rather than relying on them alone.

Q: Do I need dual-antenna heading for urban air mobility?

If the flight controller needs yaw in hover, taxi or vertiport manoeuvring, yes - dual-antenna heading delivers 0.15 degrees at a 1 m baseline and roughly 0.03 degrees at 5 m, with no calibration and no magnetic dependency. Single-antenna platforms can use GNSS with IMU fusion and treat an integrated compass as a cross-check only.

An eVTOL GNSS navigation system must deliver four things at once: centimetre RTK position, proven integrity (RAIM+/FDE), immunity to urban RF interference (AIM+), and a fix fast enough for the flight-control loop. Weight is the constraint that makes it hard. You choose between a 14 g integrated receiver, a 60 g 100 Hz board, or a 789-channel heading board — depending on mass budget and whether you need dual-antenna heading.

Talk to a GNSS engineer about your eVTOL platform

Tell us your airframe class, mass budget, correction source (NTRIP, local base, radio) and flight-controller interface — we will recommend a receiver or board and send a quote.

Request a quote · See eVTOL GNSS receiver options →

What an eVTOL GNSS navigation system must deliver

Requirement	In a UAM corridor	Spec to ask for
Approach and hover positioning	Pad tolerances; hover must not drift	RTK 0.6 cm + 0.5 ppm horizontal
Integrity assurance	A wrong fix on final approach is worse than none	RAIM+ with fault detection and exclusion
Interference rejection	5G, radar and broadcast share the spectrum	AIM+ up to 60 dB suppression
Spoofing resistance	Deliberate manipulation over populated areas	OSNMA authentication, RAIM+ cross-checks
Rate and mass budget	GNSS/IMU fusion in the control loop; every gram costs range	20–100 Hz output, PPS, 14 g integrated option

Why urban corridors break ordinary drone GNSS

Multipath. Facades and elevated roads reflect signals, and the error peaks at low altitude — exactly where landing happens. Multi-frequency reception plus APME+ mitigation is the fix.
Interference. 5G and LTE towers, radar and video downlinks raise the noise floor until tracking loops slip. AIM+ mitigation suppresses them before they reach the position solution.
Spoofing and scintillation. A false signal that looks correct is more dangerous than an obvious jam, and at low latitudes ionospheric phase distortion breaks RTK fixes more often than sky obstruction. OSNMA and IONO+ address both.
Geometry. Urban canyons mask satellites, so vertical and heading performance degrade first. Multi-constellation tracking keeps enough measurements for a fixed solution.

What RAIM+ actually buys you

RAIM+ compares redundant satellite measurements inside the receiver and flags when the position no longer matches them. Fault Detection and Exclusion then drops the offending measurement instead of letting it bias your solution. Two consequences: one faulty or spoofed signal cannot silently walk your position across the ground, and the guidance layer gets a “do not trust this fix” alarm in time to act. Note the boundary — receiver integrity monitoring feeds your approval case, it does not replace it. Set your integrity and continuity targets with your avionics integrator, then check the receiver’s protection levels against them.

Receiver options by airframe class

Option	Engine	Rate	Heading	Mitigation	Form factor	Best fit
HBEV322H integrated receiver	mosaic-G5 P3H, 789 ch	1–20 Hz	Dual-antenna 0.15° @ 1 m + compass	AIM+, APME+, LOCK+, IONO+	14 g, φ44 × 40.6 mm	Tightest mass budget
HB52H board	mosaic-G5, 789 ch	1.4 ns PPS	Dual-antenna heading, pitch, roll	AIM+, APME+, IONO+, LOCK+, RAIM+	Ultralight board	Your own enclosure
HB51 heading board	mosaic-G5 P3H, 789 ch	20 Hz	Dual-antenna 0.15° @ 1 m + RM3100	AIM+, RAIM+	65.5 × 58.4 × 13.7 mm, 86 g	Magnetic heading fallback
HB50 receiver	mosaic-X5	100 Hz, 7 s RTK init	Positioning only (HB50H adds heading)	AIM+, APME+, IONO+, OSNMA, RAIM+	7.6 × 6.9 × 1.3 cm, 60 g	High-dynamics flight control
HB59 OEM board	AsteRx-m3 Pro+, 544 ch	100 Hz, <10 ms	Dual-antenna heading, pitch, roll	AIM+, Ethernet	OEM board	Larger airframes

Figures follow Eview and Septentrio published data for the named configurations. AIM+ licensing, connector variant and interface options change the part number — confirm the option set on your quote. Browse the full GNSS boards and OEM module range if you are integrating into your own avionics bay.

Integration and procurement checklist

Antenna: EV210 (Φ27.5 × 57.6 mm, 33 ± 2 dB LNA, IP67, phase centre ±3 mm) for weight-critical airframes; EV220 adds Galileo E5b/E6 for heading pairs.
Interfaces: UART, USB-C, Ethernet or CAN to the flight computer; RTCM v3.x in for NTRIP; SBF and NMEA 0183 out.
Timing: PPS aligns IMU and GNSS samples in one clock domain — 1.4 ns on mosaic-G5 boards, 5 ns xPPS on HB50-class hardware.
Power and EMI: HB50 draws ~1.6 W typical at 3.3 V; board ratings reach −40 °C to +95 °C. Give the antenna a ground plane and route coax away from ESC and motor phase leads.
Lead time: plan several weeks on standard OEM orders and confirm whether AIM+ and your connector variant are stock or built to order.

FAQ: eVTOL GNSS navigation

What GNSS accuracy does an eVTOL need?

Centimetre RTK: 0.6 cm + 0.5 ppm horizontal on mosaic-X5 and mosaic-G5 hardware, initialising in under 10 seconds. Accuracy alone is not enough for an aircraft — integrity monitoring and interference rejection matter more than a marginal accuracy gain.

Is RTK required, or is PPP enough?

PPP gives decimetre accuracy with wide-area coverage and no base station, which suits en-route navigation. Vertiport approach, hover and landing need RTK repeatability and fast convergence. Many mosaic-family receivers support both, so PPP is a sensible fallback if the correction link drops.

How do you keep a GNSS fix in a dense city?

Handle interference before the tracking loops see it: AIM+ suppresses interfering signals up to 60 dB, while multi-frequency multi-constellation tracking keeps enough measurements for a fixed solution under partial sky view — the same approach used in UAV and drone RTK operations.

Can a receiver detect spoofing on its own?

Partly. OSNMA authenticates Galileo signals cryptographically and RAIM+ reports an integrity alarm when redundant measurements disagree. No receiver catches every scenario, so feed its alarms into the aircraft’s failsafe logic rather than relying on them alone.

Do I need dual-antenna heading for urban air mobility?

If the flight controller needs yaw in hover, taxi or vertiport manoeuvring, yes — dual-antenna heading delivers 0.15° at a 1 m baseline and roughly 0.03° at 5 m, with no calibration and no magnetic dependency. Single-antenna platforms can use GNSS with IMU fusion and treat an integrated compass (QMC5883L, RM3100) as a cross-check only, since airframe structure and motor current disturb it. PPK belongs to mapping deliverables rather than real-time control; confirm raw SBF logging if the same aircraft flies survey missions.

Next step: size the receiver to your airframe

Send us your airframe class, mass budget, accuracy and integrity targets, correction source and flight-controller interface. We will reply with a specific board or integrated receiver recommendation, antenna and baseline guidance, and a quote. Start from the GNSS for eVTOL and advanced air mobility range, or contact Eview GNSS directly.