A bright blue sky - that’s when the Remote Sensing department is running at full speed. The summer is a busy time for the APEX team. APEX is a hyperspectral camera that takes images of different areas in Europe. Four colleagues are on standby throughout the summer to make sure all the flight campaigns run smoothly. Bart Bomans coordinates the measurements and draws up the flight plans together with all parties involved. Johan Mijnendonkx is one of the three APEX operators flying all over Europe to ensure that the required images are collected.

Bart Bomans was already involved in the development and construction of the hyperspectral camera in 2010. APEX stands for Airborn Prism Experiment. “It’s a unique device developed by a Swiss-Belgian consortium on behalf of ESA, used to perform a spectral analysis of the sunlight that is reflected by the earth, while in a plane up in the air. The signal contains a huge amount of information about lots of phenomena such as the growth and health of vegetation, air pollution and water quality.”

The APEX camera

Bright blue sky

Bart was an operator on the plane for many years, but today he is mainly involved in the coordination. “We have customers from Lithuania to southern Spain. My job is to collect their questions and plan the measurements. A whole series of factors must coincide to have a successful flight. The instrument needs a bright blue sky. Therefore, we are heavily dependent on the weather forecast for our planning. But  drawing up flight plans involves a lot of work, for example when we have to fly over military zones. In the meantime, for a large number of measurements, our customers are also active in the field to take measurements on the ground . My job is to consult with all the actors and to make the necessary arrangements so that the right data can be collected.”

APEX team in front of aircraft

Always packed to go

The operators who fly along on the flights, like Johan Mijnendonckx, always have a packed suitcase ready during the summer months. “Because we depend on the weather, the measurements cannot always be planned in advance. We often don’t know in the morning where we’ll sleep at night. It’s not unusual for us to be looking for a hotel to stay at eleven o'clock at night. A good relationship with colleagues is very important because we spend a lot of time together. Of course, you have to be OK with being flexible, which is a prerequisite for this job."

Working with oxygen mask

To perform the measurements, a special aircraft is used with a hatch in the bottom above which the measuring device is mounted. The operators have to operate and control the instrument during the flight. They also coordinate with the pilots where and how to fly. The operators are seated in a kind of open cargo hold of the aircraft, which makes the job even more special.

Johan: “From an altitude of 3,000 metres, we have to wear an oxygen mask. Sometimes we even fly at an altitude of 7,000 meters. At such altitudes, we would lose consciousness without the oxygen. That’s why we get special training to recognise the symptoms of altitude sickness. There are always two of us on an airplane, so we can help each other if something goes wrong. That makes our cooperation with colleagues extra special.”

APEX flight operator with oxygen mask

Thorough preparation

This all sounds very adventurous, but the success of measurement campaigns is basically about very thorough preparation. Bart Bomans: “The tracks we fly, the altitude and the settings of the device - all of these are defined in detail in advance. The measurement results are gigabytes of data that we process afterwards. First, the raw data must be corrected. After that, researchers can start interpreting the results.”

For Bart, the variety of the job is one of the major advantages. “There are many technical and scientific aspects to the measurements, but there are also a lot of practical matters involved, such as consultation with customers, monitoring weather forecasts and coordination with air traffic control and the relevant public authorities. Not a single day here is the same as the previous one and sometimes things don’t go according to plan. Nevertheless, we always succeed in delivering the desired results.  That’s why a lot of customers have come back several times - a sign that they are satisfied.”

APEX camera images of coast