Tracks, Gaps & Delays in Tracking, What Causes This? (GPS Issues)

This article explain common issues to tracking problems. 

The Spider uses GPS information to create a position report, which is what we call a 'Spidertracks point'.  It does this at intervals according to the configuration within the website. The point is then placed into a temporary (memory) queue on the device, while an SBDIX session is established with the Iridium satellites. A Spider has the ability to store up to 10 points in its internal memory.

Once the connection is established the point is transmitted through the Iridium network and to the Spidertracks servers, across a direct IP socket from the Iridium ground station.

Under ideal conditions, this channel (from the time the point is created on the device until it is processed and posted by Spidertracks) has very low latency; generally less than 30s. The network is highly dynamic, however, and is subject to some variance in performance.

Performance is a function of many variables; from the instantaneous position of the satellites, to environmental conditions, and even as extreme as solar flares. It is considered normal for a small percentage of points to take several minutes to be transmitted under certain conditions.

Incorrect Position Reports?

Very occasionally a Spider may show different information when first switched on. This will self-correct once the Spider starts to communicate with the networks as it needs to triangulate its location.

The perfect example of this would be when the aircraft is parked whilst pre-flight checks are carried out around or in buildings. You can see the aircraft position moving on your dashboard page during this time, although it is in one location.

Although the error can be minimal on a horizontal perspective, the vertical perspective can be higher, but this should become more accurate after one or two points, once the aircraft is in the air (after the first position report).

Things that can affect the Spider from transmitting;

• Heated windshields.
• The terrain where you are flying can sometimes block the Spider from connecting to the Iridium satellites, especially if you are flying in valleys. Once you go over the mountains, the Spider will be able to connect to the satellites again and tracking should resume.
• Metal objects placed above the spider such as windows braces can affect tracking.
• Avoid placing next to other GPS equipment and compasses, move as far away as you can but make sure you have a clear view of the sky.
• If you are using Watch, avoid switching the Spider ON/OFF when parked next to buildings or when parked inside the hangar.
• If you are using Watch, try switching the Spider off as you as you are taxiing in and below the transition speed.

Here are some examples of Spider positions.

What might you see and experience if your Spider is experiencing GPS issues?

• Gaps in tracks (see below), in this track the Spider is having issues with the heated window in the aircraft.

• If you are using Watch, the Spider might take a long time to switch off (the blue LED keeps flashing and does not go out) and it may send false SOS messages.

 

What Can You Do About it?

• Check the Location.
• Do you have electrically heated windows?
• Make sure that the Spider has a clear view of the sky and is not placed under any metallic objects (ie window struts).
• Spiders should not be placed directly next to other GPS units.
• Check the GPS Fix.
• What LEDs show on the Spider?

Test your Spider outside the cockpit

Testing the Spider outside the cockpit can help eliminate whether the Spider is being affected by something in the aircraft or in a poor position. It can be tested in a car using the cigarette connector or another aircraft where you are not experiencing the issue. Test the Spider with a different cable if available.

Did this resolve your issues?

If not, please contact us at [e-mail]  with the following information;

• Spider Serial number
• Aircraft it is assigned to
• Photo of installation
• Type of aircraft