Despite the arrival of NS1 on 18 April, the main work of patrolling the North Sea from Pulham is carried out by Coastal Class airships.
In the southern part of the North Sea, the Germans have decided to contest this, and attacks were made on the airships from time to time by fighting seaplanes from Zeebrugge.
Today, On the 21st of April 1917 the coastal airship, C17, captained by Sub Lieutenant Edward George Oliphant Jackson, drifted off her course in thick weather and was subsequently shot down in flames off the North Foreland by German Hansa Brandenburg W12 seaplanes. The crew of five were killed including Jackson and:
- Observer Assistant Paymaster Raymond Alfred Price Warlters
- 2nd Class Air Mechanic John Monro
- Leading Mechanic David Farquhar
- Chief Petty Officer 3rd Class Mechanic Arthur Chivers
As a result of this loss, patrolling airships were ordered, when out of sight of land, to check their positions by wireless every hour, a proceeding which had the disadvantage that listening enemy stations could pass the information to the German seaplane commanders.