Precision over the Pond: Why Field of View is everything for Seaplane Pilots

As seaplane pilots, we know that “glassy water” is one of the most beautiful—and dangerous—conditions we face. Without visual depth perception, a RADAR altimeter becomes your best friend. But when you’re shopping for one, you’ll see a major technical spec: Field of View (FoV).

Some devices on the market use a 120° FoV, while the SkyVoice Glassy Guide 400 uses a focused 45° FoV.

Which one is better for your aircraft? Let’s dive into why a narrower “spotlight” usually beats a wide “floodlight” for seaplanes.

1. The Installation Headache (or Lack Thereof)

The biggest challenge with a 120° FoV is finding a place to put it. A 120-degree cone is massive. According to their manuals, the area below the sensor must be completely free of:

• Landing gear and floats
• Flaps and struts
• Drainage vents or antennas

On a floatplane, finding a spot on the belly that can “see” 60 degrees to the left and 60 degrees to the right without hitting a float or a spreader bar is nearly impossible. If the radar hits your own aircraft, you get false altitude returns—the device might tell you you’ve landed while you’re still 20 feet up.

With Skyvoice Glassy Guide’s 45° FoV, the “clearance cone” is much tighter. You can mount it in more locations because it’s a surgical “spotlight” that looks straight down, easily clearing your floats and gear.

2. Water Surface Reflections

Water acts like a mirror to radar waves.

• Wide Beam (120°): Sends energy out at extreme angles. On choppy water or during spray, these wide-angle waves can bounce off waves and return “clutter” to the sensor, potentially causing “jumpy” height readouts.
• Narrow Beam (45°): Focuses the energy directly at the surface beneath you. This results in a stronger, cleaner “echo” returning to the sensor, which is critical for the 1-foot accuracy needed for a smooth touchdown on glassy water.

3. Reliability vs. Attitude

Proponents of wide FoV argue that it stays “locked on” during steep turns. While true, how often are you in a 45-degree bank during your final flare onto the water? Landing is a wings-level maneuver. The SkyVoice 45° FoV is optimized for the landing environment. It provides the perfect balance: wide enough to handle standard pitch and roll during a normal approach, but narrow enough to ignore the “noise” of your own aircraft’s structure.

Summary: 120° vs. 45°