A property manager with a portfolio of branches wants an up-to-date aerial image of every site, in the same quality and the same file structure. Photographing one site is simple. Fifty sites, spread across the whole country, is a planning assignment with a drone in it.
This article describes how we approach such an assignment, based on a recent assignment covering 50 retail sites in Flanders, Brussels and Wallonia.
Step 1: the list becomes a dossier
The assignment starts with a list of addresses. That list is rarely error-free. Ours had 52 rows for 50 unique sites: two addresses appeared twice. That is one flight with two deliveries, not two flights.
Each site gets a record sheet with coordinates, a code, access details, the surroundings and the images required. That sheet follows the site through to delivery.
Step 2: each site gets an airspace status
We check the geozones for each site. On this assignment, about half were outside any zone. The other half were spread across six zones: the CTRs of Brussels, Antwerp, Ostend and Charleroi, the zone around Kortrijk-Wevelgem and a military zone. One site was on the edge of a port area with its own application procedure.
We also note the edge cases: a site 500 metres from a prison, a site just outside a zone boundary, a site along a canal where we do not fly over the water. Those edge cases help determine the order and the timing on the flying day.
Step 3: sites become flying days
With the airspace status and the addresses, we build flying days. Three rules:
- Group by region and by zone. Sites in the same CTR on the same day limit the number of applications.
- Busy places first. We fly shopping streets and town centres early in the day or at the weekend, when there are fewest people about.
- Real driving times, not the distance as the crow flies. We optimise the order for each day on the actual route. A twelve-hour flying day needs a margin for weather and unforeseen situations.
That turned 50 sites into a handful of flying days, each with a departure time, an order and an expected finish time.
Step 4: applying for permissions, with reserve dates
For sites in a CTR we apply for permission from skeyes, with a minimum lead time of 8 days in VLL1 and 15 days in VLL0. For the military zone, the port area and the other zones, we follow their own procedures. For every site with a long lead time, we apply for a reserve date at the same time.
That proved necessary. Part of the schedule had to move. Because the reserve permissions were already running and every new application was checked against its own deadline, the assignment could continue without any site having to wait out a complete new lead time.
Step 5: the flying day
At each site the pilot follows the same routine: arrival, check of the surroundings, flight, check of the images on site, departure. Where required, he calls the control tower 30 minutes in advance and reports take-off and landing. In zones with many people he works with an observer.
The images are checked for each site before he leaves. Revisiting a site because an image is out of focus costs half a day and sometimes a new application.
Step 6: one delivery
Every site is delivered with the same file names, the same viewing angles and the same quality control. The client can put the sites side by side without searching for which file belongs to which branch. During the assignment, the status of each site is visible: scheduled, applied for, flown or delivered.
What this asks of you as a client
- A correct list: address, coordinates if you have them, and a contact person for each site
- Permission from the owner or manager of each site
- A window, not a fixed day: a period of a few weeks makes it possible to plan around weather and application lead times
- One point of contact for questions during the assignment
Limits
HOVVR works with one pilot. We plan a portfolio of fifty sites over several flying days. If dozens of sites have to be flown on the same day, or the assignment requires the contracting authority's own quality system, a larger firm is a better choice. We say so in advance.
Read also: Permission in a CTR: what the lead time means for your planning