The Lohner B.I was a military reconnaissance aircraft produced in Austria-Hungary during World War I.

[2] The B.I design originated before the war[3] and was initially known as the Pfeilflieger ("Arrow-flier") on account of its sharply swept-back wings,[4] giving it an arrow-shaped plan form.

Apart from this feature, it was an otherwise conventional biplane design with two-bay, staggered wings of unequal span.

[4] Known at this time as the Type B, the army took delivery of 28 aircraft before asking Lohner to develop a version better suited for mountain-flying, leading to the B.II which replaced the B.I in production in mid 1914.

On 17 December 1913, during the war with Morocco, a Spanish expeditionary squadron of the Aeronáutica Militar became the first organized air force unit to see combat during the first systematic bombing in history by dropping aerial bombs from a Lohner Flecha airplane on the plain of Ben Karrix in Morocco.