# Design a flight tracking service like FlightRadar24: system design interview question

> Global aircraft data: late reports, conflicting sources, flight identity, and fast map updates.

Source: https://sysround.com/questions/design-flight-tracking-service-like-flightradar24
Updated: 2026-11-05


Difficulty: hard. Levels: Senior, Staff+.

## How the interviewer opens it

"Design a service that shows aircraft positions and flight status worldwide. The service receives observations from several sources and must present fresh, consistent flight tracks."

## What to clarify first

- Sources and coverage
- Source volume
- Viewers and read mix
- Latency and availability
- Report contents and disorder
- Flight identity and status
- Consistency
- Coverage gaps and map detail
- Durability and history
- Scope limits

## Scope of a strong answer

Core requirements:

- Show current aircraft positions on a world map
- Combine source reports into one current track per aircraft
- Show each flight and its current status
- Show recent positions and the age of the data

Usually out of scope:

- Aircraft control or navigation
- Receiver hardware and feed contracts
- Ticket sales and route plans
- Arrival predictions

## What interviewers probe

### Which flight an aircraft serves

Aircraft serve several flights, while flight numbers repeat and sources can disagree about assignments.

### Conflicting and late position reports

Report order does not match observation order, and repeated or faulty reports can make a plausible track appear to jump.

### The world map during busy periods

Many viewers request overlapping areas, but each aircraft moves between areas and each client holds a different view.

## Common mistakes

- Uses a flight number or call sign as the permanent identity of a track.
- Uses report arrival order as the order of aircraft movement.
- Treats repeated reports as independent proof that a position is correct.
- Infers arrival when reports stop.
- Serves every map request through a global scan or sends every observation to every viewer.
- Ignores replay effects, map removals, or source clock errors.

## The bar by level

- **Senior:** Defines flight assignment rules and source conflict rules. Explains safe replay and map cursor behavior. Uses estimates to control map work and network traffic.
- **Staff+:** Defines ownership and recovery across regions. Handles uncertain identity and historical corrections without corrupting current tracks. Quantifies freshness, availability, and cost trade-offs during failures.

Practice this question with an AI interviewer: https://sysround.com/practice/new?problem=flight-tracking


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