Babcock International Group PLC (LON:BAB) warned full-year underlying will be £540mln, or the lower end of guidance due to increased competition in helicopter hire.
Three large rival providers of helicopter services have emerged from bankruptcy, which has made the oil and gas market “tough”.
Aviation contacts for £600mln in Italy and Spain have also seen revenue delayed to future periods.
Babcock also exited its oil and gas businesses in Ghana and Congo.
The FTSE 250-listed firm is experiencing weakness in Southern Europe aviation which with the oil issues will mean an additional charge of £85mln in the accounts for the year to March.
READ: Babcock results in line as strong Marine performance offsets Aviation decline
More encouragingly, the order book and pipeline are at £18bn and £16bn respectively, and combined are at a “record level”, the company said.
Shares slipped 4% to 534.2p on Wednesday at the opening bell.