Pick the most effective word from the given options to fill in the blank so that the sentence becomes meaningful and correct: While on a routine flight, the aircraft was hit by a missile and ______ into flames.

Introduction / Context:
This fill in the blank question checks your understanding of the most natural verb used in the fixed phrase that describes a sudden fire. The sentence describes an aircraft that is hit by a missile and then suddenly goes up in flames. The aim is to choose the verb that best completes the idiomatic expression used for such a scenario in English.

Given Data / Assumptions:
- Sentence: While on a routine flight, the aircraft was hit by a missile and ______ into flames. - Options: Fired, Burst, Caught, Engulfed. - The chosen verb must fit naturally before into flames.

Concept / Approach:
The standard English expression for something suddenly starting to burn fiercely is burst into flames. The verb burst captures the idea of suddenness and intensity. The other verbs either require different prepositions or convey a slightly different meaning. Caught is usually used in the form caught fire, not caught into flames. Engulfed is used when something is surrounded or swallowed by flames, usually in the structure engulfed in flames, not engulfed into flames. Fired does not work in this structure at all. Therefore, burst is the best choice.

Step-by-Step Solution:
Step 1: Consider option A, Fired. This verb usually means to shoot or to dismiss someone from a job. The phrase fired into flames is not meaningful in this context. Step 2: Consider option B, Burst. The phrase burst into flames is a well known idiom describing a sudden outbreak of fire. Step 3: Consider option C, Caught. We commonly say caught fire, not caught into flames. The preposition into makes this combination incorrect. Step 4: Consider option D, Engulfed. This verb works with in, not into, in the phrase engulfed in flames, meaning surrounded by fire. The sentence structure here does not support that usage. Step 5: Since burst correctly forms the idiomatic phrase burst into flames, it is the only suitable option.

Verification / Alternative check:
Insert each option into the sentence. The aircraft was hit by a missile and burst into flames sounds natural and vivid. The aircraft was hit by a missile and caught into flames does not read correctly because English speakers do not use caught with into flames. The aircraft was engulfed into flames is also incorrect in standard usage. These checks confirm that burst is the only grammatically and idiomatically correct option among the four.

Why Other Options Are Wrong:
Fired is wrong because it does not collocate with into flames and does not describe the aircraft's condition after being hit. Caught is wrong because the correct expression is caught fire, and the preposition into makes the phrase unnatural. Engulfed is wrong in this structure because we say engulfed in flames, not engulfed into flames.

Common Pitfalls:
Some students focus only on the meaning of fire and pick C or D without considering exact collocations and prepositions. Remember that in exams, the most natural and widely used phrase is usually expected as the answer. Phrases like burst into flames, catch fire, and engulfed in flames are worth memorising as fixed expressions. Paying attention to such patterns in reading material and news reports will greatly improve your performance in vocabulary and usage questions.

Final Answer:
The correct word to complete the sentence is Burst, giving While on a routine flight, the aircraft was hit by a missile and burst into flames.