10 Common Mistakes That Fail OASC, AOSB, AIB Candidates

Most candidates who fail officer selection boards don't lack ability. They make preventable mistakes during preparation or on assessment day that undermine otherwise strong performance.

This guide covers the ten most common mistakes I see in coaching sessions and explains how to avoid them.

1. Spending All Your Time Planning, None on Presentation

The Mistake:

Candidates receive a planning exercise scenario with 30 minutes to analyse and build a plan. Most spend 28 minutes perfecting their solution, then panic through a rushed 2-minute presentation.

The result: a decent plan delivered poorly. They stumble through their brief, forget key points, and sound uncertain about their own solution.

Why This Fails:

Your presentation is as important as your plan. A good plan delivered with clarity and confidence beats a perfect plan delivered poorly.

Planning exercises test decision-making under time pressure. Spending all your time chasing the perfect solution demonstrates poor time management, not thoroughness.

What to Do Instead:

Allocate time for presentation preparation. Set a point where you stop analysing and commit to your plan. Use remaining time to rehearse your brief out loud.

When you rehearse, you identify unclear explanations, check your timing, and build confidence in your delivery. Candidates who skip this step waste the most valuable minutes.

For more detail on [planning exercise structure and timing](link to planning exercise guide), see our complete guide.

2. Over-Explaining After You've Answered the Question

The Mistake:

You deliver a complete interview answer. The board member nods and takes notes. Silence follows.

The instinct: keep talking. Add "just one more example". Clarify something you already explained clearly. Fill the uncomfortable silence.

The result: you dilute a strong answer with weaker points. More critically, you sound uncertain about what you just said.

Why This Fails:

Silence after your answer isn't awkward - it's the interviewer thinking or taking notes. Over-explaining signals you lack confidence in your own response.

Officers need to make definitive statements and stop. Continuing after you've answered suggests you don't recognise when you've provided sufficient information.

What to Do Instead:

When you finish your answer, stop talking. Count to five in your head if you need something to do. If the interviewer wants more detail, they'll ask.

Practice this in mock interviews. Record yourself and count how many times you keep talking after the answer is complete.

3. Using Hedging Language That Undermines Your Answers

The Mistake:

"I think maybe we could potentially restructure the approach..."

"I kind of led the team through the challenge..."

"It seemed like the right decision at the time, possibly..."

Hedging words - maybe, kind of, sort of, I think, potentially, possibly - weaken otherwise competent answers.

Why This Fails:

Hedging makes you sound uncertain about your own experiences and decisions. Officers make decisions with incomplete information and present them confidently. Constant hedging signals you lack conviction in your own judgment.

The content of your answer might be strong, but the delivery undermines everything.

What to Do Instead:

Commit to your statements. Say "The priority was..." not "I thought maybe...". Say "I decided to..." not "I kind of decided...".

Record yourself answering practice questions. Count hedging words. Re-answer without them. Notice how much stronger it sounds.

Even if your decision wasn't perfect, present it with confidence. You can acknowledge limitations without undermining your entire answer with uncertain language.

4. Memorising Answers Word-for-Word

The Mistake:

Candidates write out complete answers to expected questions. They memorise them word-for-word, then recite these scripts in interviews.

When the question changes slightly or the interviewer asks a follow-up, the memorised script doesn't fit. Candidates either force it in awkwardly or freeze trying to recall exact wording.

Why This Fails:

Memorised answers sound robotic, not natural. Interviewers recognise when you're reciting rather than thinking.

More critically, memorisation creates rigidity. You're locked into specific wording. When the situation demands flexibility, you can't adapt.

What to Do Instead:

Prepare frameworks, not scripts. Know your key examples, the outcomes you want to highlight, and flexibility to adapt to the actual question asked.

For each competency (leadership, teamwork, problem-solving), have 2-3 strong examples ready. Know the situation, your actions, and results. Practice adapting each example to different question angles.

Framework approach: "I have a leadership example from my sports team. If asked about leading under pressure, I emphasise the time constraints and stakes. If asked about leadership style, I focus on how I approached the team."

Same example. Different emphasis. Natural delivery.

Our guide on [common interview questions](link to interview questions guide) explains how to build flexible frameworks for the most frequently asked questions.

5. Choosing Fake Weaknesses in Interviews

The Mistake:

"What's your biggest weakness?"

"I'm a perfectionist."

"I work too hard."

"I care too much about getting things right."

These aren't weaknesses. They're strengths disguised as flaws, and interviewers see through them immediately.

Why This Fails:

Fake weaknesses suggest you're either dishonest or lack genuine self-awareness. Either interpretation damages your credibility.

The weakness question tests whether you've reflected honestly on your performance and whether you take action to improve. Giving a non-answer fails both tests.

What to Do Instead:

Choose a real, fixable weakness you've actively worked to improve. Structure your answer: past tense weakness + specific action taken + current improved state.

Example: "I used to struggle with delegating. I tended to take on too much myself rather than trusting my team. I've worked on this by actively assigning tasks based on people's strengths and checking in without micromanaging. It's made me a more effective team leader."

This demonstrates self-awareness and initiative to improve - exactly what the question is testing.

6. Blaming Others When Discussing Failures

The Mistake:

"Tell me about a time something went wrong."

"My team didn't follow my instructions."

"I wasn't given the right information."

"The other department didn't deliver on time."

Even if others genuinely contributed to the failure, leading with blame suggests you don't take ownership of outcomes.

Why This Fails:

Officers are accountable for their team's performance, not just their own actions. Deflecting responsibility when things go wrong signals you won't take ownership in challenging situations.

The question is testing whether you can reflect honestly on failure and identify what you could have done differently. Blaming others fails this test entirely.

What to Do Instead:

Own the failure completely. Explain what you could have done differently, what you learned, and how you've applied that learning since.

Example: "In my first leadership role, I assumed my team understood the project priorities without clearly communicating them. When we missed a deadline, I realised I hadn't set clear expectations or checked understanding. Since then, I always confirm priorities explicitly and create space for questions."

This shows accountability, learning, and behavioural change - all qualities expected in officers.

7. Talking the Most in Group Discussions

The Mistake:

Candidates think group discussions reward whoever contributes most. They dominate airtime, push their ideas forcefully, and measure success by how much they spoke.

Why This Fails:

Group discussions test whether you can make teams more effective, not whether you can win arguments.

The highest-performing candidates don't talk the most. They build on others' ideas, bring quieter members into the conversation, keep the group moving toward decisions, and facilitate progress without dominating.

Talking constantly often means you're not listening, not building on others' contributions, and not demonstrating the collaborative leadership expected in officer roles.

What to Do Instead:

Focus on making the group more effective. Ask yourself: "Did I help this group reach a better decision than we would have without me?"

Practical behaviours:

• Build on others' ideas instead of just pushing your own

• Bring quieter candidates into the conversation

• Track time and keep the group moving

• Disagree constructively without shutting people down

Quality of contribution matters more than quantity.

8. Training to Barely Pass Fitness Standards

The Mistake:

Candidates train just enough to scrape through the bleep test or meet minimum press-up requirements. They view fitness as a box to tick, not a foundation for performance.

On assessment day, they pass the fitness test but have nothing left for the mental challenges that follow. By afternoon interviews or planning exercises, they're exhausted and their performance suffers.

Why This Fails:

Assessment day is long and demanding. Multiple interviews, planning exercises, group discussions, and physical tests. Marginal fitness means physical demands consume all your capacity.

Better fitness provides: more energy across exercises, faster recovery between tasks, mental clarity under physical stress, and confidence going into assessment day.

What to Do Instead:

Train above the standard. Don't aim to barely pass - aim to have capacity left when tested.

Physical margin creates mental margin. Being comfortably above fitness standards means you can focus mental energy on performance, not survival.

Better fitness won't guarantee success, but marginal fitness guarantees you're operating at a disadvantage.

9. Starting Preparation Too Late

The Mistake:

Candidates receive their assessment date six weeks out. They think "I'll start preparing next week." Then "I'll start next week." Then they're three weeks away, panicking, trying to cram months of preparation into days.

Late preparation forces damage limitation, not genuine improvement.

Why This Fails:

Quality preparation takes time. You need to:

• Identify weak areas and address them systematically

• Practice planning exercises until the format feels natural

• Build interview frameworks through repeated refinement

• Develop fitness gradually without injury risk

• Build confidence through evidence of improvement

Six weeks of focused preparation can work. Three weeks of panic cramming cannot.

What to Do Instead:

Start preparing when you get your assessment date, not when you panic about it.

Ideal timeline: 3-4 months gives you time to identify weaknesses, practice properly, build fitness sustainably, and develop genuine confidence through preparation.

Can you prepare in less time? Yes. But you're limiting your performance potential. Early preparation enables real improvement. Late preparation forces you to work around weaknesses you can't fix in time.

10. Trying to Solve Everything in Planning Exercises

The Mistake:

Planning exercise scenarios present 8-10 problems. Candidates try to address every single one, producing shallow plans with no depth.

They spend limited time spreading themselves across all issues, never developing any solution properly.

Why This Fails:

You don't have time to solve everything thoroughly. Attempting to do so demonstrates poor prioritisation - a critical leadership skill.

Strong planning performance means identifying the 3-4 critical priorities and solving them well. Weak performance means trying to solve everything inadequately.

What to Do Instead:

Identify what matters most. Use the consequence test: "What happens if I DON'T address this first?"

• Life/safety issues = priority one

• Mission-critical tasks = priority two

• Everything else = acknowledge but deprioritise

Focus your plan on critical priorities. Address them thoroughly. Acknowledge other issues exist but explain why they're secondary to your main priorities.

Assessors want to see you can distinguish urgent from important under pressure, not that you can mention every problem in the scenario.

How These Mistakes Connect

These ten mistakes share a common thread: they reveal gaps in preparation, self-awareness, or understanding of what officer selection tests.

Candidates who make multiple mistakes aren't less capable than those who don't. They've either prepared incorrectly or misunderstood what strong performance looks like.

The good news: these are all preventable through proper preparation.

How to Avoid These Mistakes

Structured Preparation

Work systematically through each assessment component:

• Planning exercises: practice the format, get feedback, refine your approach

• Interviews: build flexible frameworks, not memorised scripts

• Group discussions: understand facilitation vs domination

• Fitness: train above minimum standards

  
  

Quality Feedback

Solo practice identifies some problems. Quality feedback identifies all of them.

Record yourself. Review critically. Better yet, work with someone who understands what strong performance looks like and can identify specific gaps.

Sufficient Time

Three months gives you time to identify weaknesses, address them properly, and build genuine confidence. Six weeks works if focused. Three weeks forces damage limitation.

Start when you get your assessment date, not when you panic about it.

Honest Self-Assessment

Most mistakes come from lack of self-awareness. Record your practice sessions. Count hedging words. Notice when you over-explain. Identify where you dominate instead of facilitate.

Honest assessment of current performance enables targeted improvement.

Final Thoughts

These ten mistakes cost candidates places at OASC, AOSB, and AIB every selection cycle. None of them reflect lack of ability - they reflect preventable preparation gaps.

Avoid these mistakes through:

• Structured preparation across all assessment areas

• Quality feedback that identifies specific weaknesses

• Sufficient time to improve properly

• Honest self-assessment of current performance

The candidates who succeed aren't necessarily the most naturally talented. They're the ones who prepared correctly and avoided preventable mistakes.

Get Expert Assessment Preparation

MAP works one-to-one with candidates preparing for OASC, AOSB, and AIB. We identify specific gaps in your preparation and give you targeted feedback on planning exercises, interviews, and group discussions.

Book a coaching session or download the Planning Exercise Guide to see how we can help you prepare.